Practice Test

Q1) How much work does the road do on the cycle? Show Answer

Q2) How much work does the cycle do on the road? Show Answer

Q3) The sign of work done by a force on a body is important to understand. For
(i) work done by a man in lifting a bucket out of a wall by means of a rope tide to the bucket
(ii) work one by friction on a body sliding down an inclined plane
(iii) work done by a applied force on a body moving on a rough horizontal plane with uniform velocity
(iv) work done by the resistive force of air on a vibrating pendulum in bringing it to rest. Choose the sign of work done Show Answer

Q4) When a conservative force does positive work on a body; the potential energy of the body Show Answer

Q5) Two identical ball bearings in contact with each other and resting on a frictionless table are hit head on by another ball bearing of the same mass moving initially with a speed v. If the collision is elastic, which of the following is a possible result of the collision? Show Answer

Q6) A trolley of mass 300 kg carrying a sandbag of 25 kg is moving uniformly with a speed of 36 km/h on a frictionless track. After a while, sand starts leaking out of a hole on the floor of the trolley at the rate of 0.05 kg/s. Speed of the trolley when the entire sand bag is empty is Show Answer

Q7) The linear momentum of a body is increased by 50%. The kinetic energy will be increased by Show Answer

Q8) Two masses of 1 g and 9 g are moving with equal kinetic energies. The ratio of the magnitudes of their respective linear momentum is Show Answer

Q9) Change in magnitude of velocity of bead between point A and B is Show Answer

Q10) Time taken by bead to move between points A and B is Show Answer

Q11) The average force exterted by the bead on the part AB of the wire is Show Answer

Q12) A machine which is 70% efficient raises a 10 kg body through a certain distance and spends 100 J of energy. The body is then released. On reaching the ground, the kinetic energy of the body will be Show Answer

Q13) A glass marble dropped from a certain height above the horizontal surface reaches the surface in time t and then continues to bounce up and down. The time in which the marble finally comes to rest is Show Answer

Q14) A nucleus ruptures into two nuclear parts which have their velocity ratio equal to 2 : 1. The ratio of their respective nuclear sizes (nuclear radii) is Show Answer

Q15) Two billiard balls of the same size and mass are in contact on a billiard table. A third ball of the same size and mass strikes them symmetrically and remains at rest after the impact. The coefficient of restitution between the balls is Show Answer

Q16) A stone is dropped from the top of a tall tower. The ratio of the kinetic energy of the stone at the end of three second to the increase in the kinetic energy of the stone during the next three second is Show Answer

Q17) The negative of the space rate of change of potential energy is equal to Show Answer

Q18) A conservative force moves a body round a closed path. Work done will be Show Answer

Q19) Statement 1 : If the work done by force other than conservative forces is zero, then mechanical energy is conserved.
Statement 2 : The work done by non-conservative forces is always negative. Show Answer

Q20) As the block slides down, which of the following quantities associated with the system remains conserved? Show Answer

Q21) If there would have been friction between wedge and block, which of the following quantities would still remain conserved? Show Answer

Q22) If there is no friction anywhere, the speed of the wedge, as the block leaves the wedge, is Show Answer

Q23) A 2 kg body is dropped from a height of 0.4 m on a spring of force constant 2000 N/m. The maximum compression of the spring is: Show Answer

Q24) A projectile is fired with kinetic energy 1 kJ. If its range maximum the kinetic energy at the highest point is: Show Answer

Q25) When K.E. of the body is increased by 300%, the momentum of the body is increased by: Show Answer

Q26) Two masses of 1 g and 4 g are moving with equal kinetic energy. The ratio of their linear momenta is: Show Answer

Q27) The momentum of body is numerically equal to its K.E. What is the velocity of body? Show Answer

Q28) A tennis ball dropped from a height of 2 m rebounds only 1.5 m after hitting the ground. What fraction of energy is lost in the impact? Show Answer

Q29) A light and a heavy body have equal K.E. which one has greater momentum? Show Answer

Q30) A uniform chain of length 'L' and mass M is lying on a smooth table and one-third of its length is hanging vertically down over the edge, the work done to pull the hanging part on to the table is: Show Answer

Q31) A ball falls freely from a height of 10 m. If 40% of the energy is lost due to impact, the ball will go up to a height (after one impact) given by: Show Answer

Q32) A solid ball of density half that of water falls freely under gravity from a height of 19.6 m and then enters water. Up to what depth it will sink? Also find how much time will the ball take to come again to the water surface? (Neglect air and water resistances); Show Answer

Q33) A body falling freely under gravity has a P.E. equal to 9 times the K.E. at a particular instant. When the velocity of the body is doubled than the velocity at a certain instant, the ratio between P.E. and K.E. will be: Show Answer

Q34) A bullet, when fired at a fixed plate has its velocity decreased by 50% after penetrating through 30 cm of its thickness. What is the additional thickness required for the plate so that the bullet may just comes to rest after penetrating it? Show Answer

Q35) If the force acting on a body is inversely proportional to its speed the K.E. of a body is: Show Answer

Q36) A ball falling from a height of 5 m rebounds to 1.8 m height. Then the ratio of velocities of the ball after and before rebound is:
Show Answer

Q37) A body A experiences perfectly elastic collision with a stationary body B. If after collision the bodies fly apart in the opposite direction with equal velocities, the mass ratio of A and B is: Show Answer

Q38) A heavy nucleus at rest breaks into two fragments which fly off with velocities 8 : 1. The ratio of radii of the fragments is: Show Answer

Q39) A bullet fired into a fixed target loses 20% of its K.E. in penetrating 1 cm. Find the total distance penetrated by bullet before it comes to rest: Show Answer

Q40) A running man has half the kinetic energy of that of a boy of half his mass. The man speeds up by one metre per second and then has the same kinetic energy as that of the boy. What are the original speeds of the boy and man? Show Answer

Q41) Which of the following is true? Show Answer

Q42) A body of mass 5 kg has momentum of 10 kg m/s. When a force of 0.2 N is applied on it for 10 seconds, what is the change in its kinetic energy? Show Answer

Q43) A body of mass 5 kg explodes into 3 fragments having masses in ratio of 2 : 1 : 1. The fragments with equal masses fly in merely far direction with speed 15 m/sec. What will be the velocity of lighter fragment:
Show Answer

Q44) A body of mass 10 kg at rest is acted upon simultaneously by two forces 4 N and 3 N at right angles to each other. The kinetic energy of the body at the end of 10 s is: Show Answer

Q45) A force 10 N displace an object by 10 m. If work done is 50 J then direction of force makes an angle with direction of displacement: Show Answer

Q46) 250 N force is required to raise 75 kg mass with a pulley. If rope is pulled 12 m them the load is lifted to 3m, the efficiency of pulley system will be: Show Answer

Q47) A metal ball of mass 2 kg moving with speed of 36 km/hr has a head on collision with a stationary ball of mass 3 kg. If after collision, both the balls move together, then the loss in kinetic energy due to collision is: Show Answer

Q48) A motor pump lifts 300 kg of water per minute from a well 20 m deep and delivers to height of 20 m. Its power is : Show Answer

Q49) The kinetic energy of a body becomes four times its initial value. The new linear momentum will be: Show Answer

Q50) Potential energy in a spring when stretched by 2 cm is U. Its potential energy, when stretched by 10 cm is: Show Answer

Q51) An ideal spring with spring-constant k is hung from the ceilling and a block of mass M is attached to its lower end. The mass is released with the spring initially unstretched. Then the maximum extension in the spring is: Show Answer

Q52) A 50 kg man with 20 kg load on his head climbs up 20 steps of 0.25 m height each. The work done in climbing is: Show Answer

Q53) A pump motor is used to deliver water at a certain rate from a given pipe. To obtain in twice as much water from the same pipe in the same time, power of the motor has to be increased to: Show Answer

Q54) If kinetic energy of a body is increased by 300 percent, then percentage change in momentum will be: Show Answer

Q55) If force and displacement of particle in the direction of force are doubled. Work would be: Show Answer

Q56) A machine, which is 75% efficient, uses 12 J of energy in lifting up a 1 kg mass through a certain distance. The mass is then allowed to fall through that distance. The velocity at the ends of its fall is (in m/s): Show Answer

Q57) A body of mass 2 kg makes an elastic collision with another body at rest and continues to move in the original direction with one fourth of its original speed. The mass of the second body which collides with the first body is: Show Answer

Q58) A quarter horse power motor runs at a speed of 600 r.p.m. Assuming 40% efficiency the work done by the motor in one rotation will be: Show Answer

Q59) A car of mass 1000 kg accelerates uniformly from rest to a velocity of 54 km/hour in 5 s. The average power of the engine during this period in watts is (neglect friction) : Show Answer

Q60) An elevator is run by the cables at constant speed. The total work done by the elevator is: Show Answer

Q61) A wire suspended vertically from one of its ends is stretched by attaching a weight of 200 N to the lower end. The weight stretches the wire by 1mm. Then the elastic energy stored in the wire is: Show Answer

Q62) When a long spring is stretched by 2 cm, its potential energy is U. if the spring is stretched by 10 cm, the potential energy stored in it will be: Show Answer

Q63) A neutron makes a head-on elastic collision with a stationary deuteron. The fractional energy loss of the neutron in the collision is: Show Answer

Q64) Two masses 1 g and 4 g are moving equal kinetic energies. The ratio of magnitudes of their momentum is: Show Answer

Q65) A ball of mass 2 kg and another of mass 4 kg are dropped together from a 60 feet tall building. After a fall of 30 feet each towards earth, their respective kinetic energies will be in the ratio of: Show Answer

Q66) A ball is dropped from a height of 20 cm. Ball rebounds to a height of 10 cm. What is the loss of energy? Show Answer

Q67) A bomb of mass 3.0 kg explodes in air into two pieces of masses 2.0 kg and 1.0 kg. The smaller mass goes at a speed of 80 m/s. The total energy imparted to the two fragments is: Show Answer

Q68) One milligram of matter is converted into energy. The energy released will be: Show Answer

Q69) If the kinetic energy of a body increases by 0.1%, the percentage increase of its momentum will be: Show Answer

Q70) A ball is released from the top of the tower. The ratio of work done by force of gravity in first, second and third second of the motion of the ball is: Show Answer

Q71) A shell of mass 200 gm is ejected form a gun of mass 4 kg by an explosion that generates 1.05 kJ of energy. The initial velocity of the shell is: Show Answer

Q72) A uniform metal chain is placed on a rough table such that one end of it hangs down over the edge of the table. When one third of its length hangs over the edge, the chain starts sliding. Then the coefficient of static friction is: Show Answer

Q73) Potential energy of a long spring when stretched by 2 cm is U. What is the P.E. when spring is stretched by 8 cm? Show Answer

Q74) An engine pumps water continuously through a hose. Water leaves the hose with a velocity v and m is the mass per unit length of the water jet. What is the rate at which kinetic energy is imparted of water? Show Answer

Q75) A ball moving with velocity 2 m/s collides head on with another stationary ball of double the mass. If the coefficient of restitution is 0.5, then their velocities (in m/s) after collision will be: Show Answer

Q76) An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of 2m/s. The mass per unit length of water in the pipe is 100 kg/m. What is the power of the engine? Show Answer

Q77) The potential energy of a system increases if work is done: Show Answer

Q78) If the unit of force and length each be increased by four times, then the unit of energy is increased by Show Answer

Q79) A man pushes a wall and fails to displace it. He does Show Answer

Q80) The same retarding force is applied to stop a train. The train stops after 80 m. If the speed is doubled, then the distance will be Show Answer

Q81) A body moves a distance of 10 m along a straight line under the action of a force of 5 N. If the work done is 25 joules, the angle which the force makes with the direction of motion of the body is Show Answer

Q82) You lift a heavy book from the floor of the room and keep it in the book-shelf having a height 2 m. In this process you take 5 seconds. The work done by you will depend upon Show Answer

Q83) A body of mass m kg is lifted by a man to a height of one metre in 30 sec. Another man lifts the same mass to the same height in 60 sec. The work done by them are in the ratio Show Answer

Q84) Which of the following is a scalar quantity Show Answer

Q85) A force of 5 N acts on a 15 kg body initially at rest. The work done by the force during the first second of motion of the body is Show Answer

Q86) The work done against gravity in taking 10 kg mass at 1m height in 1sec will be Show Answer

Q87) A body of mass 10kg at rest is acted upon simultaneously by two forces 4 N and 3N at right angles to each other. The kinetic energy of the body at the end of 10 sec is Show Answer

Q88) A cylinder of mass 10kg is sliding on a plane with an initial velocity of 10m/s. If coefficient of friction between surface and cylinder is 0.5, then before stopping it will describe Show Answer

Q89) A 50kg man with 20kg load on his head climbs up 20 steps of 0.25m height each. The work done in climbing is Show Answer

Q90) In an explosion a body breaks up into two pieces of unequal masses. In this Show Answer

Q91) Which of the following is a unit of energy Show Answer

Q92) If force and displacement of particle in direction of force are doubled. Work would be Show Answer

Q93) A uniform chain of length 2m is kept on a table such that a length of 60cm hangs freely from the edge of the table. The total mass of the chain is 4kg. What is the work done in pulling the entire chain on the table Show Answer

Q94) A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle, the motion of the particle takes place in a plane. It follows that Show Answer

Q95) A ball of mass m moves with speed v and strikes a wall having infinite mass and it returns with same speed then the work done by the ball on the wall is Show Answer

Q96) The kinetic energy acquired by a body of mass m is travelling some distance s, starting from rest under the actions of a constant force, is directly proportional to Show Answer

Q97) A man starts walking from a point on the surface of earth (assumed smooth) and reaches diagonally opposite point. What is the work done by him Show Answer

Q98) It is easier to draw up a wooden block along an inclined plane than to haul it vertically, principally because Show Answer

Q99) Two bodies of masses 1 kg and 5 kg are dropped gently from the top of a tower. At a point 20 cm from the ground, both the bodies will have the same Show Answer

Q100) A ball is released from the top of a tower. The ratio of work done by force of gravity in first, second and third second of the motion of the ball is Show Answer

Q101) A spring of force constant 10 N/m has an initial stretch 0.20 m. In changing the stretch to 0.25 m, the increase in potential energy is about Show Answer

Q102) The potential energy of a certain spring when stretched through a distance ‘S’ is 10 joule. The amount of work (in joule) that must be done on this spring to stretch it through an additional distance ‘S’ will be Show Answer

Q103) Two springs of spring constants 1500 N/m and 3000 N/m respectively are stretched with the same force. They will have potential energy in the ratio Show Answer

Q104) A spring 40 mm long is stretched by the application of a force. If 10 N force required to stretch the spring through 1 mm, then work done in stretching the spring through 40 mm is Show Answer

Q105) The force constant of a wire is k and that of another wire is When both the wires are stretched through same distance, then the work done Show Answer

Q106) A body of mass 0.1 kg moving with a velocity of 10 m/s hits a spring (fixed at the other end) of force constant 1000 N/m and comes to rest after compressing the spring. The compression of the spring is Show Answer

Q107) A spring of force constant 800 N/m has an extension of 5cm. The work done in extending it from 5cm to 15 cm is Show Answer

Q108) When a spring is stretched by 2 cm, it stores 100 J of energy. If it is stretched further by 2 cm, the stored energy will be increased by Show Answer

Q109) A spring when stretched by 2 mm its potential energy becomes 4 J. If it is stretched by 10 mm, its potential energy is equal to Show Answer

Q110) A mass of 0.5kg moving with a speed of 1.5 m/s on a horizontal smooth surface, collides with a nearly weightless spring of force constant k=50 N/m . The maximum compression of the spring would be Show Answer

Q111) A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement x is proportional to Show Answer

Q112) A spring with spring constant k when stretched through 1 cm, the potential energy is U. If it is stretched by 4 cm. The potential energy will be Show Answer

Q113) If a long spring is stretched by 0.02 m, its potential energy is U. If the spring is stretched by 0.1 m, then its potential energy will be Show Answer

Q114) The spring extends by x on loading, then energy stored by the spring is :
(if T is the tension in spring and k is spring constant)
Show Answer

Q115) Which one of the following is not a conservative force Show Answer

Q116) Work done in raising a box depends on Show Answer

Q117) A light and a heavy body have equal momenta. Which one has greater K.E Show Answer

Q118) A body at rest may have Show Answer

Q119) If the momentum of a body is increased n times, its kinetic energy increases Show Answer

Q120) When work is done on a body by an external force, its Show Answer

Q121) The bob of a simple pendulum (mass m and length l) dropped from a horizontal position strikes a block of the same mass elastically placed on a horizontal frictionless table. The K.E. of the block will be Show Answer

Q122) From a stationary tank of mass 125000 pound a small shell of mass 25 pound is fired with a muzzle velocity of 1000 ft/sec. The tank recoils with a velocity of Show Answer

Q123) A bomb of 12 kg explodes into two pieces of masses 4 kg and 8 kg. The velocity of 8kg mass is 6 m/sec. The kinetic energy of the other mass is Show Answer

Q124) Two masses of 1 gm and 4 gm are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is Show Answer

Q125) If the K.E. of a body is increased by 300%, its momentum will increase by Show Answer

Q126) A light and a heavy body have equal kinetic energy. Which one has a greater momentum ? Show Answer

Q127) If the linear momentum is increased by 50%, the kinetic energy will increase by Show Answer

Q128) A free body of mass 8 kg is travelling at 2 meter per second in a straight line. At a certain instant, the body splits into two equal parts due to internal explosion which releases 16 joules of energy. Neither part leaves the original line of motion finally Show Answer

Q129) If the K.E. of a particle is doubled, then its momentum will Show Answer

Q130) If the stone is thrown up vertically and return to ground, its potential energy is maximum Show Answer

Q131) The energy stored in wound watch spring is Show Answer

Q132) A car travelling at a speed of 30 km/hour is brought to a halt in 8 m by applying brakes. If the same car is travelling at 60 km/hour, it can be brought to a halt with the same braking force in Show Answer

Q133) Tripling the speed of the motor car multiplies the distance needed for stopping it by Show Answer

Q134) If the kinetic energy of a body increases by 0.1%, the percent increase of its momentum will be Show Answer

Q135) If velocity of a body is twice of previous velocity, then kinetic energy will become Show Answer

Q136) Two bodies A and B having masses in the ratio of 3 : 1 possess the same kinetic energy. The ratio of their linear momenta is then Show Answer

Q137) In which case does the potential energy decrease Show Answer

Q138) A sphere of mass m, moving with velocity V, enters a hanging bag of sand and stops. If the mass of the bag is M and it is raised by height h, then the velocity of the sphere was Show Answer

Q139) The force constant of a weightless spring is 16 N/m. A body of mass 1.0 kg suspended from it is pulled down through 5 cm and then released. The maximum kinetic energy of the system (spring + body) will be Show Answer

Q140) Two bodies with kinetic energies in the ratio of 4 : 1 are moving with equal linear momentum. The ratio of their masses is Show Answer

Q141) If the kinetic energy of a body becomes four times of its initial value, then new momentum will Show Answer

Q142) A bullet is fired from a rifle. If the rifle recoils freely, then the kinetic energy of the rifle is Show Answer

Q143) Two bodies of masses 2m and m have their K.E. in the ratio 8 : 1, then their ratio of momenta is Show Answer

Q144) A bomb of 12 kg divides in two parts whose ratio of masses is 1 : 3. If kinetic energy of smaller part is 216 J, then momentum of bigger part in kg-m/sec will be Show Answer

Q145) A 4 kg mass and a 1 kg mass are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is Show Answer

Q146) If the increase in the kinetic energy of a body is 22%, then the increase in the momentum will be Show Answer

Q147) If momentum is increased by 20%, then K.E. increases by Show Answer

Q148) The kinetic energy of a body of mass 2 kg and momentum of 2 Ns is Show Answer

Q149) The decrease in the potential energy of a ball of mass 20 kg which falls from a height of 50 cm is Show Answer

Q150) An object of 1 kg mass has a momentum of 10 kg m/sec then the kinetic energy of the object will be Show Answer

Q151) A ball is released from certain height. It loses 50% of its kinetic energy on striking the ground. It will attain a height again equal to Show Answer

Q152) A 0.5 kg ball is thrown up with an initial speed 14 m/s and reaches a maximum height of 8.0m. How much energy is dissipated by air drag acting on the ball during the ascent Show Answer

Q153) An ice cream has a marked value of 700 kcal. How many kilowatt- hour of energy will it deliver to the body as it is digested Show Answer

Q154) A particle of mass 'm' and charge 'q' is accelerated through a potential difference of 'V' volt. Its energy is Show Answer

Q155) A running man has half the kinetic energy of that of a boy of half of his mass. The man speeds up by 1m/s so as to have same K.E. as that of the boy. The original speed of the man will be Show Answer

Q156) The mass of two substances are 4 gm and 9 gm respectively. If their kinetic energies are same, then the ratio of their momenta will be Show Answer

Q157) If the momentum of a body is increased by 100%, then the percentage increase in the kinetic energy is Show Answer

Q158) If a body looses half of its velocity on penetrating 3 cm in a wooden block, then how much will it penetrate more before coming to rest Show Answer

Q159) A bomb of mass 9kg explodes into 2 pieces of mass 3kg and 6kg. The velocity of mass 3kg is 1.6 m/s, the K.E. of mass 6kg is Show Answer

Q160) Two masses of 1kg and 16kg are moving with equal K.E. The ratio of magnitude of the linear momentum is Show Answer

Q161) Two bodies moving towards each other collide and move away in opposite directions. There is some rise in temperature of bodies because a part of the kinetic energy is converted into Show Answer

Q162) A particle of mass m at rest is acted upon by a force F for a time t. Its Kinetic energy after an interval t is Show Answer

Q163) The potential energy of a weight less spring compressed by a distance a is proportional to Show Answer

Q164) Two identical blocks A and B, each of mass 'm' resting on smooth floor are connected by a light spring of natural length L and spring constant K, with the spring at its natural length. A third identical block 'C' (mass m) moving with a speed v along the line joining A and B collides with A. the maximum compression in the spring is Show Answer

Q165) Two bodies of masses m and 4 m are moving with equal K.E. The ratio of their linear momentums is Show Answer

Q166) The kinetic energy of a body of mass 3 kg and momentum 2 Ns is Show Answer

Q167) A ball of mass 2kg and another of mass 4kg are dropped together from a 60 feet tall building. After a fall of 30 feet each towards earth, their respective kinetic energies will be in the ratio of Show Answer

Q168) Four particles given, have same momentum which has maximum kinetic energy Show Answer

Q169) A body moving with velocity v has momentum and kinetic energy numerically equal. What is the value of v Show Answer

Q170) If a man increase his speed by 2 m/s , his K.E. is doubled, the original speed of the man is Show Answer

Q171) Which among the following, is a form of energy Show Answer

Q172) A body is moving with a velocity v, breaks up into two equal parts. One of the part retraces back with velocity v. Then the velocity of the other part is Show Answer

Q173) If a shell fired from a cannon, explodes in mid air, then Show Answer

Q174) Masses of two substances are 1 g and 9 g respectively. If their kinetic energies are same, then the ratio of their momentum will be Show Answer

Q175) A body of mass 5 kg is moving with a momentum of 10 kg-m/s. A force of 0.2 N acts on it in the direction of motion of the body for 10 seconds. The increase in its kinetic energy is Show Answer

Q176) If the momentum of a body increases by 0.01%, its kinetic energy will increase by Show Answer

Q177) 1 a.m.u. is equivalent to Show Answer

Q178) A spherical ball of mass 20 kg is stationary at the top of a hill of height 100 m. It slides down a smooth surface to the ground, then climbs up another hill of height 30 m and finally slides down to a horizontal base at a height of 20 m above the ground. The velocity attained by the ball is Show Answer

Q179) If a force F is applied on a body and it moves with a velocity v, the power will be Show Answer

Q180) A man is riding on a cycle with velocity 7.2 km/hr up a hill having a slope 1 in 20. The total mass of the man and cycle is 100 kg. The power of the man is Show Answer

Q181) A 12 HP motor has to be operated 8 hours/day. How much will it cost at the rate of 50 paisa/kWh in 10 days Show Answer

Q182) A motor boat is travelling with a speed of 3.0 m/sec. If the force on it due to water flow is 500 N, the power of the boat is Show Answer

Q183) An electric motor exerts a force of 40 N on a cable and pulls it by a distance of 30 m in one minute. The power supplied by the motor (in Watts) is Show Answer

Q184) An electric motor creates a tension of 4500 newton in a hoisting cable and reels it in at the rate of 2 m/sec. What is the power of electric motor Show Answer

Q185) A weight lifter lifts 300 kg from the ground to a height of 2 meter in 3 second. The average power generated by him is Show Answer

Q186) A car of mass ‘m’ is driven with acceleration ‘a’ along a straight level road against a constant external resistive force ‘R’. When the velocity of the car is ‘V’, the rate at which the engine of the car is doing work will be Show Answer

Q187) The average power required to lift a 100 kg mass through a height of 50 metres in approximately 50 seconds would be Show Answer

Q188) From a waterfall, water is falling down at the rate of 100 kg/s on the blades of turbine. If the height of the fall is 100 m, then the power delivered to the turbine is approximately equal to Show Answer

Q189) A car of mass 1250 kg is moving at 30m/s. Its engine delivers 30 kW while resistive force due to surface is 750N. What max acceleration can be given in the car Show Answer

Q190) A 60 kg man runs up a staircase in 12 seconds while a 50 kg man runs up the same staircase in 11, seconds, the ratio of the rate of doing their work is Show Answer

Q191) A pump motor is used to deliver water at a certain rate from a given pipe. To obtain twice as much water from the same pipe in the same time, power of the motor has to be increased to Show Answer

Q192) What average horsepower is developed by an 80 kg man while climbing in 10 s a flight of stairs that rises 6 m vertically Show Answer

Q193) A car of mass 1000 kg accelerates uniformly from rest to a velocity of 54 km/hour in 5s. The average power of the engine during this period in watts is (neglect friction) Show Answer

Q194) A quarter horse power motor runs at a speed of 600 r.p.m. Assuming 40% efficiency the work done by the motor in one rotation will be Show Answer

Q195) The power of pump, which can pump 200 kg of water to a height of 50 m in 10 sec, will be Show Answer

Q196) From an automatic gun a man fires 360 bullet per minute with a speed of 360 km/hour. If each weighs 20 g, the power of the gun is Show Answer

Q197) A man does a given amount of work in 10 sec. Another man does the same amount of work in 20 sec. The ratio of the output power of first man to the second man is Show Answer

Q198) The coefficient of restitution e for a perfectly elastic collision is Show Answer

Q199) The principle of conservation of linear momentum can be strictly applied during a collision between two particles provided the time of impact is Show Answer

Q200) A shell initially at rest explodes into two pieces of equal mass, then the two pieces will Show Answer

Q201) A sphere of mass m moving with a constant velocity u hits another stationary sphere of the same mass. If e is the coefficient of restitution, then the ratio of the velocity of two spheres after collision will be Show Answer

Q202) Two solid rubber balls A and B having masses 200 and 400 gm respectively are moving in opposite directions with velocity of A equal to 0.3 m/s. After collision the two balls come to rest, then the velocity of B is Show Answer

Q203) Two perfectly elastic particles P and Q of equal mass travelling along the line joining them with velocities 15 m/sec and 10 m/sec. After collision, their velocities respectively (in m/sec) will be Show Answer

Q204) A lead ball strikes a wall and falls down, a tennis ball having the same mass and velocity strikes the wall and bounces back. Check the correct statement Show Answer

Q205) When two bodies collide elastically, then Show Answer

Q206) Two balls at same temperature collide. What is conserved Show Answer

Q207) A body of mass 5 kg explodes at rest into three fragments with masses in the ratio 1 : 1 : 3. The fragments with equal masses fly in mutually perpendicular directions with speeds of 21 m/s. The velocity of the heaviest fragment will be Show Answer

Q208) A body of mass ‘M’ collides against a wall with a velocity v and retraces its path with the same speed. The change in momentum is (take initial direction of velocity as positive) Show Answer

Q209) In an elastic collision of two particles the following is conserved Show Answer

Q210) A smooth sphere of mass M moving with velocity u directly collides elastically with another sphere of mass m at rest. After collision their final velocities are V and v respectively. The value of v is Show Answer

Q211) A body of mass m having an initial velocity v, makes head on collision with a stationary body of mass M. After the collision, the body of mass m comes to rest and only the body having mass M moves. This will happen only when Show Answer

Q212) A shell of mass m moving with velocity v suddenly breaks into 2 pieces. The part having mass m/4 remains stationary. The velocity of the other shell will be Show Answer

Q213) A rubber ball is dropped from a height of 5 m on a planet where the acceleration due to gravity is not known. On bouncing, it rises to 1.8 m. The ball loses its velocity on bouncing by a factor of Show Answer

Q214) A metal ball falls from a height of 32 metre on a steel plate. If the coefficient of restitution is 0.5, to what height will the ball rise after second bounce Show Answer

Q215) A ball of mass 10 kg is moving with a velocity of 10 m/s. It strikes another ball of mass 5 kg which is moving in the same direction with a velocity of 4 m/s. If the collision is elastic, their velocities after the collision will be, respectively Show Answer

Q216) A body of mass 2 kg collides with a wall with speed 100 m/s and rebounds with same speed. If the time of contact was 1/50 second, the force exerted on the wall is Show Answer

Q217) A body falls on a surface of coefficient of restitution 0.6 from a height of 1 m. Then the body rebounds to a height of Show Answer

Q218) A ball is dropped from a height h. If the coefficient of restitution be e, then to what height will it rise after jumping twice from the ground Show Answer

Q219) A ball of weight 0.1 kg coming with speed 30 m/s strikes with a bat and returns in opposite direction with speed 40 m/s, then the impulse is (Taking final velocity as positive) Show Answer

Q220) A billiard ball moving with a speed of 5 m/s collides with an identical ball originally at rest. If the first ball stops after collision, then the second ball will move forward with a speed of Show Answer

Q221) If two balls each of mass 0.06 kg moving in opposite directions with speed 4 m/s collide and rebound with the same speed, then the impulse imparted to each ball due to other is Show Answer

Q222) A body of mass 50 kg is projected vertically upwards with velocity of 100 m/sec. 5 seconds after this body breaks into 20 kg and 30 kg. If 20 kg piece travels upwards with 150 m/sec, then the velocity of other block will be Show Answer

Q223) A steel ball of radius 2 cm is at rest on a frictionless surface. Another ball of radius 4cm moving at a velocity of 81 cm/sec collides elastically with first ball. After collision the smaller ball moves with speed of Show Answer

Q224) A space craft of mass M is moving with velocity V and suddenly explodes into two pieces. A part of it of mass m becomes at rest, then the velocity of other part will be Show Answer

Q225) A ball hits a vertical wall horizontally at 10m/s bounces back at 10 m/s Show Answer

Q226) A bullet of mass 50 gram is fired from a 5 kg gun with a velocity of 1km/s. the speed of recoil of the gun is Show Answer

Q227) A body falling from a height of 10m rebounds from hard floor. If it loses 20% energy in the impact, then coefficient of restitution is Show Answer

Q228) Two bodies having same mass 40 kg are moving in opposite directions, one with a velocity of 10 m/s and the other with 7 m/s. If they collide and move as one body, the velocity of the combination is Show Answer

Q229) A body at rest breaks up into 3 parts. If 2 parts having equal masses fly off perpendicularly each after with a velocity of 12m/s, then the velocity of the third part which has 3 times mass of each part is Show Answer

Q230) A particle falls from a height h upon a fixed horizontal plane and rebounds. If e is the coefficient of restitution, the total distance travelled before rebounding has stopped is Show Answer

Q231) A big ball of mass M, moving with velocity u strikes a small ball of mass m, which is at rest. Finally small ball obtains velocity u and big ball v. Then what is the value of v Show Answer

Q232) A body of mass 5 kg moving with a velocity 10m/s collides with another body of the mass 20 kg at, rest and comes to rest. The velocity of the second body due to collision is Show Answer

Q233) A ball of mass m moving with velocity V, makes a head on elastic collision with a ball of the same mass moving with velocity 2V towards it. Taking direction of V as positive velocities of the two balls after collision are Show Answer

Q234) A body of mass 2kg makes an elastic collision with another body at rest and continues to move in the original direction with one fourth of its original speed. The mass of the second body which collides with the first body is Show Answer

Q235) In the elastic collision of objects Show Answer

Q236) A neutron makes a head-on elastic collision with a stationary deuteron. The fractional energy loss of the neutron in the collision is Show Answer

Q237) A body of mass m is at rest. Another body of same mass moving with velocity V makes head on elastic collision with the first body. After collision the first body starts to move with velocity Show Answer

Q238) A body of mass M moves with velocity v and collides elastically with a another body of mass m (M>>m) at rest then the velocity of body of mass m is Show Answer

Q239) A space craft of mass 'M' and moving with velocity 'v' suddenly breaks in two pieces of same mass m. After the explosion one of the mass 'm' becomes stationary. What is the velocity of the other part of craft Show Answer

Q240) A ball is allowed to fall from a height of 10 m. If there is 40% loss of energy due to impact, then after one impact ball will go up to Show Answer

Q241) Which of the following statements is true Show Answer

Q242) A tennis ball dropped from a height of 2 m rebounds only 1.5 m after hitting the ground. What fraction of its energy is lost in the impact Show Answer

Q243) A body of mass m moving with velocity v makes a head-on collision with another body of mass 2 m which is initially at rest. The loss of kinetic energy of the colliding body (mass m) is Show Answer

Q244) The quantities remaining constant in a collision are Show Answer

Q245) An inelastic ball is dropped from a height of 100 m. Due to earth, 20% of its energy is lost. To what height the ball will rise Show Answer

Q246) A ball is projected vertically down with an initial velocity from a height of 20 m onto a horizontal floor. During the impact it loses 50% of its energy and rebounds to the same height. The initial velocity of its projection is Show Answer

Q247) A tennis ball is released from height h above ground level. If the ball makes inelastic collision with the ground, to what height will it rise after third collision Show Answer

Q248) A sphere collides with another sphere of identical mass. After collision, the two spheres move. The collision is inelastic. Then the angle between the directions of the two spheres is Show Answer

Q249) A particle of mass m moving eastward with a speed v collides with another particle of the same mass moving northward with the same speed v. The two particles coalesce on collision. The new particle of mass 2m will move in the north-easterly direction with a velocity Show Answer

Q250) The coefficient of restitution e for a perfectly inelastic collision is Show Answer

Q251) When two bodies stick together after collision, the collision is said to be Show Answer

Q252) A bullet of mass a and velocity b is fired into a large block of mass c. The final velocity of the system is Show Answer

Q253) A completely inelastic collision is one in which the two colliding particles Show Answer

Q254) A bullet hits and gets embedded in a solid block resting on a horizontal frictionless table. What is conserved ? Show Answer

Q255) A body of mass 2 kg moving with a velocity of 3 m/sec collides head on with a body of mass 1 kg moving in opposite direction with a velocity of 4 m/sec. After collision, two bodies stick together and move with a common velocity which in m/sec is equal to Show Answer

Q256) A body of mass m moving with a constant velocity v hits another body of the same mass moving with the same velocity v but in the opposite direction and sticks to it. The velocity of the compound body after collision is Show Answer

Q257) 9. A body of mass m moving with a constant velocity v hits another body of the same mass moving with the same velocity v but in the opposite direction and sticks to it. if another body is at rest, then velocity of the compound body after collision is Show Answer

Q258) A bag (mass M) hangs by a long thread and a bullet (mass m) comes horizontally with velocity v and gets caught in the bag. Then for the combined (bag + bullet) system Show Answer

Q259) A 50 g bullet moving with velocity 10 m/s strikes a block of mass 950 g at rest and gets embedded in it. The loss in kinetic energy will be Show Answer

Q260) A particle of mass m moving with velocity v strikes a stationary particle of mass 2m and sticks to it. The speed of the system will be Show Answer

Q261) A moving body of mass m and velocity 3 km/h collides with a rest body of mass 2m and sticks to it. Now the combined mass starts to move. What will be the combined velocity Show Answer

Q262) If a skater of weight 3 kg has initial speed 32 m/s and second one of weight 4 kg has 5 m/s. After collision, they have speed (couple) 5 m/s. Then the loss in K.E. is Show Answer

Q263) A ball is dropped from height 10 m. Ball is embedded in sand 1 m and stops, then Show Answer

Q264) A metal ball of mass 2 kg moving with a velocity of 36 km/h has an head on collision with a stationary ball of mass 3 kg. If after the collision, the two balls move together, the loss in kinetic energy due to collision is Show Answer

Q265) A body of mass 2kg is moving with velocity 10 m/s towards east. Another body of same mass and same velocity moving towards north collides with former and coalsces and moves towards north-east. Its velocity is Show Answer

Q266) Which of the following is not a perfectly inelastic collision Show Answer

Q267) A mass of 20 kg moving with a speed of 10m/s collides with another stationary mass of As a result of the collision, the two masses stick together. The kinetic energy of the composite mass will be Show Answer

Q268) The quantity that is not conserved in an inelastic collision is Show Answer

Q269) A body of mass 40kg having velocity 4 m/s collides with another body of mass 60kg having velocity 2 m/s. If the collision is inelastic, then loss in kinetic energy will be Show Answer

Q270) A bullet of mass m moving with velocity v strikes a block of mass M at rest and gets embedded into it. The kinetic energy of the composite block will be Show Answer

Q271) In an inelastic collision, what is conserved Show Answer

Q272) Two bodies of masses 0.1 kg and 0.4 kg move towards each other with the velocities 1 m/s and 0.1 m/s respectively, After collision they stick together. In 10 sec the combined mass travels Show Answer

Q273) A body of mass 4 kg moving with velocity 12 m/s collides with another body of mass 6 kg at rest. If two bodies stick together after collision, then the loss of kinetic energy of system is Show Answer

Q274) Which of the following is not an example of perfectly inelastic collision Show Answer

Q275) A ball hits the floor and rebounds after inelastic collision. In this case Show Answer

Q276) A uniform chain of length L and mass M is lying on a smooth table and one third of its length is hanging vertically down over the edge of the table. If g is acceleration due to gravity, the work required to pull the hanging part on to the table is Show Answer

Q277) If g is the acceleration due to gravity on the earth's surface, the gain in the potential energy of an object of mass m raised from the surface of earth to a height equal to the radius of the earth R, is Show Answer

Q278) A lorry and a car moving with the same K.E. are brought to rest by applying the same retarding force, then Show Answer

Q279) The kinetic energy acquired by a mass m in travelling a certain distance d starting from rest under the action of a constant force is directly proportional to Show Answer

Q280) An open knife edge of mass 'm' is dropped from a height 'h' on a wooden floor. If the blade penetrates upto the depth 'd' into the wood, the average resistance offered by the wood to the knife edge is Show Answer

Q281) Consider the following two statements
1. Linear momentum of a system of particles is zero
2. Kinetic energy of a system of particles is zero
Then
Show Answer

Q282) A body is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t is proportional to Show Answer

Q283) A vessel at rest explodes into three pieces. Two pieces having equal masses fly off perpendicular to one another with the same velocity 30 meter per second. The third piece has three times mass of each of other piece. The magnitude and direction of the velocity of the third piece will be Show Answer

Q284) A body of mass m moving with velocity v collides head on with another body of mass 2m which is initially at rest. The ratio of K.E. of colliding body before and after collision will be Show Answer

Q285) A particle P moving with speed v undergoes a head -on elastic collision with another particle Q of identical mass but at rest. After the collision Show Answer

Q286) A set of n identical cubical blocks lies at rest parallel to each other along a line on a smooth horizontal surface. The separation between the near surfaces of any two adjacent blocks is L. The block at one end is given a speed v towards the next one at time . All collisions are completely inelastic, then Show Answer

Q287) A particle is dropped from a height h. A constant horizontal velocity is given to the particle. Taking g to be constant every where, kinetic energy E of the particle w. r. t. time t is correctly shown in Show Answer

Q288) A particle, initially at rest on a frictionless horizontal surface, is acted upon by a horizontal force which is constant in size and direction. A graph is plotted between the work done (W) on the particle, against the speed of the particle, (v). If there are no other horizontal forces acting on the particle the graph would look like Show Answer

Q289) Which of the following graphs is correct between kinetic energy (E), potential energy (U) and height (h) from the ground of the particle Show Answer

Q290) The graph between and v is Show Answer

Q291) A body moves from rest with a constant acceleration. Which one of the following graphs represents the variation of its kinetic energy K with the distance travelled x ? Show Answer

Q292) The diagrams represent the potential energy U of a function of the inter-atomic distance r. Which diagram corresponds to stable molecules found in nature Show Answer

Q293) A particle is placed at the origin and a force F = kx is acting on it (where k is positive constant). If =0, the graph U(x) of versus x will be (where U is the potential energy function) Show Answer

Q294) Assertion :
A person working on a horizontal road with a load on his head does no work.
Reason :
No work is said to be done, if directions of force and displacement of load are perpendicular to each other.
Show Answer

Q295) Assertion :
The work done during a round trip is always zero.
Reason :
No force is required to move a body in its round trip.
Show Answer

Q296) Assertion :
Work done by friction on a body sliding down an inclined plane is positive.
Reason : Work done is greater than zero, if angle between force and displacement is acute or both are in same direction.
Show Answer

Q297) Assertion : When a gas is allowed to expand, work done by gas is positive.
Reason : Force due to gaseous pressure and displacement (of piston) are in the same direction.
Show Answer

Q298) Assertion :
A light body and heavy body have same momentum. Then they also have same kinetic energy.
Reason :
Kinetic energy does not depend on mass of the body.
Show Answer

Q299) Assertion :
The instantaneous power of an agent is measured as the dot product of instantaneous velocity and the force acting on it at that instant.
Reason :
The unit of instantaneous power is watt.
Show Answer

Q300) Assertion :
The change in kinetic energy of a particle is equal to the work done on it by the net force.
Reason :
Change in kinetic energy of particle is equal to the work done only in case of a system of one particle.
Show Answer

Q301) Assertion :
A spring has potential energy, both when it is compressed or stretched.
Reason :
In compressing or stretching, work is done on the spring against the restoring force.
Show Answer

Q302) Assertion : Comets move around the sun in elliptical orbits. The gravitational force on the comet due to sun is not normal to the comet’s velocity but the work done by the gravitational force over every complete orbit of the comet is zero.
Reason : Gravitational force is a non conservative force.
Show Answer

Q303) Assertion :
The rate of change of total momentum of a many particle system is proportional to the sum of the internal forces of the system.
Reason :
Internal forces can change the kinetic energy but not the momentum of the system.
Show Answer

Q304) Assertion : Water at the foot of the water fall is always at different temperature from that at the top.
Reason :
The potential energy of water at the top is converted into heat energy during falling.
Show Answer

Q305) Assertion :
The power of a pump which raises 100 kg of water in 10sec to a height of 100 m is 10 KW.
Reason :
The practical unit of power is horse power.
Show Answer

Q306) Assertion : According to law of conservation of mechanical energy change in potential energy is equal and opposite to the change in kinetic energy.
Reason : Mechanical energy is not a conserved quantity
Show Answer

Q307) Assertion : When the force retards the motion of a body, the work done is zero.
Reason :
Work done depends on angle between force and displacement.
Show Answer

Q308) Assertion :
In an elastic collision of two bodies, the momentum and energy of each body is conserved.
Reason :
If two bodies stick to each other, after colliding, the collision is said to be perfectly elastic.
Show Answer

Q309) Assertion :
A body cannot have energy without having momentum but it can have momentum without having energy.
Reason : Momentum and energy have same dimensions.
Show Answer

Q310) Assertion : Power developed in circular motion is always zero.
Reason :
Work done in case of circular motion is zero.
Show Answer

Q311) Assertion :
A kinetic energy of a body is quadrupled, when its velocity is doubled.
Reason :
Kinetic energy is proportional to square of velocity.
Show Answer

Q312) Assertion :
A quick collision between two bodies is more violent than slow collision, even when initial and final velocities are identical.
Reason :
The rate of change of momentum determine that force is small or large.
Show Answer

Q313) Assertion :
Work done by or against gravitational force in moving a body from one point to another is independent of the actual path followed between the two points.
Reason : Gravitational forces are conservative forces
Show Answer

Q314) Assertion :
Wire through which current flows gets heated.
Reason :
When current is drawn from a cell, chemical energy is converted into heat energy.
Show Answer

Q315) Assertion : Graph between potential energy of a spring versus the extension or compression of the spring is a straight line.
Reason :
Potential energy of a stretched or compressed spring, proportional to square of extension or compression.
Show Answer

Q316) Assertion : Heavy water is used as moderator in nuclear reactor.
Reason :
Water cool down the fast neutron.
Show Answer

Q317) Assertion : Mass and energy are not conserved separately, but are conserved as a single entity called mass-energy.
Reason :
Mass and energy conservation can be obtained by Einstein equation for energy.
Show Answer

Q318) Assertion :
In case of bullet fired from gun, the ratio of kinetic energy of gun and bullet is equal to ratio of mass of bullet and gun.
Reason :
In firing, momentum is conserved
Show Answer

Q319) Assertion : Power of machine gun is determined by both, the number of bullet fired per second and kinetic energy of bullets.
Reason :
Power of any machine is defined as work done (by it) per unit time.
Show Answer

Q320) Assertion :
A work done in moving a body over a closed loop is zero for every force in nature.
Reason :
Work done does not depend on nature of force.
Show Answer

Q321) Assertion : Mountain roads rarely go straight up the slope.
Reason :
Slope of mountains are large therefore more chances of vehicle to slip from roads.
Show Answer

Q322) Assertion :
Soft steel can be made red hot by continued hammering on it, but hard steel cannot.
Reason :
Energy transfer in case of soft iron is large as in hard steel.

Show Answer

Q323) A horizontal force of 5 N is required to maintain a velocity of 2 m/s for a block of 10 kg mass sliding over a rough surface. The work done by this force in one minute is Show Answer

Q324) What is the shape of the graph between the speed and kinetic energy of a body Show Answer

Q325) When a body moves with some friction on a surface Show Answer

Q326) A bullet of mass m moving with velocity v strikes a suspended wooden block of mass M. If the block rises to a height h, the initial velocity of the block will be Show Answer

Q327) There will be decrease in potential energy of the system, if work is done upon the system by Show Answer

Q328) The slope of kinetic energy displacement curve of a particle in motion is Show Answer

Q329) The energy required to accelerate a car from 10 m/s to 20 m/s is how many times the energy required to accelerate the car from rest to 10 m/s Show Answer

Q330) The kinetic energy of a body decreases by 36%. The decrease in its momentum is Show Answer

Q331) A bomb of mass 3m kg explodes into two pieces of mass m kg and 2m kg. If the velocity of m kg mass is 16 m/s, the total kinetic energy released in the explosion is Show Answer

Q332) A neutron travelling with a velocity v and K.E. E collides perfectly elastically head on with the nucleus of an atom of mass number A at rest. The fraction of total energy retained by neutron is Show Answer

Q333) A ball moving with speed v hits another identical ball at rest. The two balls stick together after collision. If specific heat of the material of the balls is S, the temperature rise resulting from the collision is Show Answer

Q334) A bag of sand of mass M is suspended by a string. A bullet of mass m is fired at it with velocity v and gets embedded into it. The loss of kinetic energy in this process is Show Answer

Q335) The potential energy of a certain spring when stretched through a distance ‘S’ is 10 joule. The amount of work (in joule) that must be done on this spring to stretch it through an additional distance ‘S’ will be Show Answer

Q336) If the kinetic energy of a body is increased 2 times , its momentum will Show Answer

Q337) A steel ball of radius 2 cm is at rest on a frictionless surface. Another ball of radius 4 cm moving at a velocity of 81 cm/sec collides elastically with first ball. After collision the smaller ball moves with speed of Show Answer

Q338) A man does a given amount of work in 10 s. Another man does the same amount of work in 20 s. The ratio of the output power of first man to the second man is Show Answer

Q339) The force constant of a wire is k and that of another wire is 2k. When both the wires are stretched through same distance, then the work done Show Answer

Q340) Consider the following statements. A and B and identify the correct answer given below.
I. Body initially at rest is acted upon by a constant force. The rate of change of its kinetic energy varies linearly with time.
II. When a body is at rest, it must be in equilibrium. Show Answer

Q341) A body at rest breaks into two pieces with unequal mass Show Answer

Q342) A mass of 50 kg is raised through a certain height by a machine whose efficiency is 90%, the energy is 5000 J. If the mass is now released, its KE on hitting the ground shall be Show Answer

Q343) A body of mass 2 kg is projected at 20 m/s at an angle of 60° above the horizontal. Power on the block due to the gravitational force at its highest point is Show Answer

Q344) An engine pumps water through a hose pipe. Water passes through the pipe and leaves it with a velocity of 2 m/s. The mass per unit length of water in the pipe is 100 kg/m. What is the power of the engine Show Answer

Q345) The bodies of masses 1 kg and 5 kg are dropped gently from the top of a tower. At a point 20 cm from the ground, both the bodies will have the same Show Answer

Q346) A rubber ball is dropped from a height of 5 m on a planet where the acceleration due to gravity is not known. On bouncing, it rises to1.8 m. The ball loses its velocity on bouncing by a factor of Show Answer

Q347) The potential energy of a certain spring when stretched through a distance s is 10 J. The amount of work (in joule) that must be done on this spring to stretch it through additional distance s will be Show Answer

Q348) The energy required to accelerate a car from 10 m/s to 20 m/s is how many times the energy required to accelerate the car from rest to 10 m/s Show Answer

Q349) A uniform chain of length L and mass M is lying on a smooth table and one third of its length is hanging vertically down over the edge of the table. If g is acceleration due to gravity, the work required to pull the hanging part on to the table is Show Answer

Q350) A mass m is attached to the end of a rod of length l. The mass goes around a vertical circular path with the other end hinged at the centre. What should be the minimum velocity of mass at the bottom of the circle, so that the mass complete the circle? Show Answer

Q351) A bullet of mass a and velocity b is fired into a large block of mass c. The final velocity of the system is Show Answer

Q352) A body of mass 10 kg is moving on a horizontal surface by applying a force of 10 N in forward direction. If
body moves with constant velocity, the work done by force of fiction for a displacement of 2m is Show Answer

Q353) A ball dropped from a height of 2m rebounds to a height of 1.5 m after hitting the ground. Then the
percentage of energy lost is Show Answer

Q354) Which of the following statements is wrong? Show Answer

Q355) Which of the following graphs show variation of potential energy (U) with position x. Show Answer

Q356) A rope ladder with a length l carrying a man with a mass m at its end is attached to the basket of balloon
with a mass M. The entire system is in equilibrium in the air. As the man climbs up the ladder into the
balloon, the balloon descends b y a height h. Then the potential energy of the man Show Answer

Q357) A particle is projected at 60° to the horizontal with a kinetic energy K. The kinetic energy at the highest
point is Show Answer

Q358) Which of the following graphs is correct between kinetic energy (E), potential energy (U) and height (h)
from the ground of the particle Show Answer

Q359) A 2 kg block slides on a horizontal floor with a speed of 4 m/s. It strikes a uncompressed spring, and compresses it till the block is motionless. The kinetic friction force is 15 N and spring constant is 10,000 N/m. The spring compresses by Show Answer

Q360) Quantity/Quantities remaining constant in a collision is/are Show Answer

Q361) A billiards player hits a stationary ball by an identical ball to pocket the target ball in a corner pocket that is at an angle of 35° with respect to the direction of motion of the first ball. Assuming the collision as elastic and that friction and rotational motion are not important, the angle made by the target ball with respect to the incoming ball is Show Answer

Q362) A machine which is 75% efficient uses 12 J of energy in lifting up a 1 kg mass through a certain distance. The mass is then allowed to fall through, that distance. The velocity of the ball at the end of its fall is Show Answer

Q363) A body of mass M moves with velocity v and collides elastically with a another body of mass m(M>>m) at rest then the velocity of body of mass m is Show Answer

Q364) A particle, initially at rest on a frictionless horizontal surface, is acted upon by a horizontal force which is constant in size and direction. A graph is plotted between the work done (W) on the particle, against the speed of the particle, (v). If there are no other horizontal forces acting on the particle the graph would look like Show Answer

Q365) A body of mass 50 kg is projected vertically upwards with velocity of 100 m/sec. 5 seconds after this body breaks into 20 kg and 30 kg. If 20 kg piece travels upwards with 150 m/sec, then the velocity of the block will be Show Answer

Q366) Two solid rubber balls A and B having masses 200 and 400 g respectively are moving in opposite
directions with velocity of A equal to 0.3m/s. After collision the two balls come to rest, then the velocity of
B is Show Answer

Q367) A space craft of mass M and moving with velocity v suddenly breaks in two pieces of same mass m. After
the explosion one of the mass m becomes stationary. What is the velocity of the other part of craft? Show Answer

Q368) A spherical ball of mass 20 kg is stationary at the top of a hill of height 100 m. It slides down a smooth
surface to the ground, then climbs up another hill of height 30 m and finally slides down to a horizontal
base at a height of 20 m above the ground. The velocity attained by the ball is Show Answer

Q369) Which of the following statements are incorrect?
(i)If there were no friction, Work need to be done to move a body up an inclined plane is zero.(ii)If there were no friction, moving vehicles could not be stopped even by locking the brakes.
(iii)As the angle of inclination is increased, the normal reaction on the body placed on it increases.
(iv)A duster weighing 0.5 kg is pressed against a vertical board with a force of 11 N. If the coefficient of friction is 0.5, the work done in rubbing it upward through a distance of 10 cm is 0.55J. Show Answer

Q370) A body of mass 5 kg is placed at the origin, and can move only on the x-axis. A force of 10 N is acting on it in a direction making an angle of 60° with the x-axis and displaces it along the x-axis by 4 metres. The work done by the force is Show Answer

Q371) If the unit of force and length each be increased by four times, then the unit of energy is increased by Show Answer

Q372) A billiard ball moving with a speed of 5 m/s collides with an identical ball originally at rest. If the first ball stops after collision, then the second ball will move forward with a speed of Show Answer

Q373) A body of mass 5 kg is thrown vertically up with a kinetic energy of 490 J. The height at which the kinetic energy of the body becomes half of the original value is Show Answer

Q374) A 0.5 kg ball is thrown up with an initial speed 14 m/s and reaches a maximum height of 8.0m. How much energy is dissipated by air drag acting on the ball during the ascent Show Answer

Q375) A particle is released from a height s. At certain height its kinetic energy is three times its potential energy. The height and speed of the particle at that instant are respectively Show Answer

Q376) A ball of mass 2 kg and another of mass 4 kg are dropped together from a 60 ft tall building .After a fall of 30 ft each towards earth ,their respective kinetic energies will be in the ratio of Show Answer

Q377) When a spring is stretched by 2 cm, it stores 100 J of energy. If it is stretched further by 2 cm, the stored energy will be increased by Show Answer

Q378) A shell of mass m moving with velocity v suddenly breaks into 2 pieces. The part having mass m/4 remains stationary. The velocity of the other shell will be Show Answer

Q379) A light and a heavy body have equal kinetic energy. Which one has a greater momentum Show Answer

Q380) A bag (mass M) hangs by a long thread and a bullet (mass m) comes horizontally with velocity v and gets caught in the bag. Then for the combined (bag + bullet) system Show Answer

Q381) If the linear momentum is increased by 50%, then kinetic energy will be increased by Show Answer

Q382) A shell of mass 200 gm is ejected from a gun of mass 4 kg by an explosion that generates 1.05 kg of energy. The initial velocity of the shell is Show Answer

Q383) A body of mass m moving with velocity v collides head on another body of mass 2m which is initially at rest. The ratio of KE of colliding body before and after collision body before and after collision will be Show Answer

Q384) A block of mass 5kg is resting on a smooth surface. At what angle a force of 20N be acted on the body so that it will acquired a kinetic energy of 40J after moving 4m Show Answer

Q385) A long spring, when stretched by x cm has a potential energy U. On increasing the length of spring by stretching to nx cm, the potential energy stored in the spring will be Show Answer

Q386) When a force is applied on a moving body, its motion is retarded. Then the work done is Show Answer

Q387) If a body of mass 3 kg is dropped from the top of a tower of height 25 m, then its kinetic energy after 3 s will be Show Answer

Q388) A spring of force constant 800 N/m has an extension of 5cm. The work done in extending it from 5 cm to 15 cm is Show Answer

Q389) A body moving with a velocity v, breaks up into two equal parts. One of the part retraces back with velocity v.Then, the velocity of the other part is Show Answer

Q390) Four particles given, have same momentum. Which has maximum kinetic energy Show Answer

Q391) In which case does the potential energy decrease Show Answer

Q392) A body moves a distance of 10 m along a straight line under action of 5 N force. If work done is 25 J, then
angle between the force and direction of motion of the body will be Show Answer

Q393) A body of mass 5 kg moving with a velocity 10 m/s collides with another body of the mass 20 kg at, rest
and comes to rest. The velocity of the second body due to collision is Show Answer

Q394) It is easier to draw up a wooden block along an inclined plane than to haul it vertically, principally because Show Answer

Q395) A sphere of mass m moving with a constant velocity u hits another stationary sphere of the same mass. If e
is the coefficient of restitution, then the ratio of the velocity of two spheres after collision will be Show Answer

Q396) A bullet of mas m moving with velocity v strikes a block of mass M at rest and gets embedded into it. The
kinetic energy of the composite block will be Show Answer

Q397) If momentum is increased by 20%, then kinetic energy increases by Show Answer

Q398) A particle falls from a height h upon a fixed horizontal plane and rebounds. If e is the coefficient of restitution, the total distance travelled before rebounding has stopped is Show Answer

Q399) Statement I Two particles moving in the same direction do not lose all their energy in a completely inelastic collision.
Statement II Principle of conservation of momentum holds true for all kinds of collisions. Show Answer

Q400) A ball is dropped from a height h. If the coefficient of restitution be e, then to what height will it rise after jumping twice from the ground Show Answer

Q401) A rubber ball is dropped from a height of 5 m on a planet, where the acceleration due to gravity is not known. On bouncing it rises to 1.8 m. The ball loses its velocity on bouncing by a factor of Show Answer

Q402) A bullet is fired from a rifle. If the riffle recoils freely, then the kinetic energy of the rifle is Show Answer

Q403) In an inelastic collision, what is conserved Show Answer

Q404) A ball is dropped from height 20 m. If coefficient of restitution is 0.9, what will be the height attained after first bounce? Show Answer

Q405) A particle is moving under the influence of a force given by F=kx where k is a constant and x is the distance moved. The energy (in joules) gained by the particle in moving from x=0 to x=3 is Show Answer

Q406) A ball is projected vertically upwards with a certain initial speed. Another ball of the same mass is projected at an angle of 60° with the vertical with the same initial speed. At highest points of their journey, the ratio of their potential energies will be Show Answer

Q407) If the K.E. of a body is increased by 300%, its momentum will increase by Show Answer

Q408) A ball is projected vertically down with an initial velocity from a height of 20 m onto a horizontal floor. During the impact it loses 50% of its energy and rebounds to the same height. The initial velocity of its projection is Show Answer

Q409) Identify the wrong statement Show Answer

Q410) If a shell fired from a cannon, explodes in mid air, then Show Answer

Q411) A body of mass 2 kg is thrown up vertically with kinetic energy of 490 J. The height at which the kinetic energy of the body becomes half of its original value is? Show Answer

Q412) A particle is moving under the influence of a force given by F=kx ,where k is a constant and x is the distance moved. The energy (in joule )gained by the particle in moving from x=0 to x=3 is Show Answer

Q413) The kinetic energy acquired by a mass m in travelling a certain distance d starting from rest under the action of a constant force is directly proportional to Show Answer

Q414) Statement I In an elastic collision between two bodies, the relative speed of the bodies after collision is equal to the relative speed before the collision.
Statement II Inan elastic collision, the linear momentum of the system is conserved. Show Answer

Q415) A ball is released from the top of a tower. The ratio of work done by force of gravity in first, second and third second of the motion of the ball is Show Answer

Q416) A smooth sphere of mass M moving with velocity u directly collides elastically with another sphere of mass m at rest. After collision their final velocities are V and v respectively. The value of v is Show Answer

Q417) If a force F is applied on a body and it moves with a velocity v, the power will be Show Answer

Q418) The work done in pulling up a block of wood weighing 2 kN for a length of 10 m on a smooth plane inclined at an angle of 15° with the horizontal is [sin15°=0.2588] Show Answer

Q419) A wire is stretched under a force. If the wire suddenly snaps the temperature of the wire Show Answer

Q420) A ball of mass 2kg and another of mass 4kg are dropped together from a 60 feet tall building. After a tall of 30 feet each towards earth, their respective kinetic energies will be in the ratio of Show Answer

Q421) The blocks of mass m each are connected to a spring of spring constant k as shown in figure. The maximum displacement in the block is Show Answer

Q422) In an elastic collision of two particles the following is conserved Show Answer

Q423) A rod AB of mass 10 kg and length 4 m rests on a horizontal floor with end A fixed so as to rotate it in vertical plane about perpendicular axis passing through A. If the work done on the rod is 100 J, the height to which the end B be raised vertically above the floor is Show Answer

Q424) Choose the incorrect statement Show Answer

Q425) An elastic string of unstretched length L and force constant k is stretched by a small length x. It is further stretched by another small length y. The work done in the second stretching is Show Answer

Q426) A ball is dropped from a height h on a floor of coefficient of restitution e.The total distance covered by the ball just before second hit is Show Answer

Q427) A bomb of mass 9 kg explodes into two parts. One part of mass 3 kg moves with velocity 16 m/s ,then the KE of the other part is Show Answer

Q428) A body of mass ‘M’ collides against a wall with a velocity v and retraces its path with the same speed. The change in momentum is (take initial direction of velocity as positive) Show Answer

Q429) A wire of length L suspended vertically from a rigid support is made to suffer extension l in its length by
applying a force F. The work is Show Answer

Q430) A man pushes a wall and falls to displace it. He does Show Answer

Q431) A spring with spring constant k when stretched through 1 cm the potential energy is U.If it is stretched by
4 cm ,the potential energy will be Show Answer

Q432) A particle is released from a height h, At a certain height; its KE is two times its potential energy. Height
and speed of the particle at that instant are Show Answer

Q433) A constant power p is applied to a car starting from rest. If v is the velocity of the car at time t, then Show Answer

Q434) A space craft of mass ‘M’ and moving with velocity ‘v’ suddenly breaks in two pieces of same mass m. After
the explosion one of the mass ‘m’ becomes stationary. What is the velocity of the other part of craft Show Answer

Q435) A body of mass 2 kg is moving with velocity 10 m/s towards east. Another body of same mass and same velocity moving towards north collides with former and coalesces and moves towards north-east. Its velocity is Show Answer

Q436) A ball moves in a frictionless inclined table without slipping. The work done by the table surface on the ball is Show Answer

Q437) In a head on elastic collision of a very heavy body moving at v with a light body at rest, velocity of heavy body after collision is Show Answer

Q438) A particle is dropped from a height h. A constant horizontal velocity is given to the particle. Taking g to be constant every where, kinetic energy E of the particle w.r.t. time t is correctly shown in Show Answer

Q439) The slope of the kinetic energy displacement curve of a particle in motion is Show Answer

Q440) A quarter horse power motor runs at a speed of 600 r.p.m. Assuming 40% efficiency the work done by the
motor in one rotation will be Show Answer

Q441) From an automatic gun a man fires 360 bullet per minute with a speed of 360 km/hour. If each weighs
20 g, the power of the gun is Show Answer

Q442) Two bodies of masses 2m and m have their K.E. in the ratio 8: 1, then their ratio of momenta is Show Answer

Q443) A particle is released from a height S. At certain height its kinetic energy is three times its potential energy.
The height and speed of the particle at that instant are respectively Show Answer

Q444) If velocity of a body is twice of previous velocity, then kinetic energy will become Show Answer

Q445) A body is initially at rest. It undergoes one-dimensional motion with constant acceleration. The power
delivered to it at time t is proportional to Show Answer

Q446) For inelastic collision between two spherical rigid bodies Show Answer

Q447) A cylinder of mass 10kg is sliding on a plane with an initial velocity of 10 m/s. If coefficient of friction between surface and cylinder is 0.5, then before stopping it will describe Show Answer

Q448) A stone is dropped from the top of a tall tower. The ratio of the kinetic energy of the stone at the end of three seconds to the increase in the kinetic energy of the stone during the next three seconds is Show Answer

Q449) A body of mass m is at rest. Another body of same mass moving with velocity V makes head on elastic collision with the first body. After collision the first body starts to move with velocity Show Answer

Q450) The bob of a simple pendulum (mass m and length l) dropped from a horizontal position strikes a block of the same mass elastically placed on a horizontal frictionless table. The K.E. of the block will be Show Answer

Q451) A bullet hits and gets embedded in a solid block resting on a frictionless surface .In this process which one of the following is correct? Show Answer

Q452) The height of the dam, in a hydroelectric power station is 10m. In order to generate 1 MW of electric power, the mass of water (in kg/s) that must fall per second on the blades of the turbines Show Answer

Q453) In an inelastic collision Show Answer

Q454) A ball dropped from a height of 2 m rebounds to a height of 1.5 m after hitting the ground. Then the
percentage of energy lost is Show Answer

Q455) A bomb of mass 3.0 kg explodes in air into two pieces of masses 2.0 kg and 1.0 kg. The smaller mass goes
at a speed of 80 m/s. The total energy imparted to the two fragments is Show Answer

Q456) An athlete in the Olympic covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in
the range Show Answer

Q457) A body of mass m moving with a constant velocity v hits another body of the same mass moving with the
same velocity v but in the opposite direction and sticks to it. The velocity of the compound body after
collision is Show Answer

Q458) An engine pumps water continuously through a hole. Speed with which water passes through the hole
nozzle is v and k is the mass per unit length of the water jet as it leaves the nozzle. Find the rate at which
kinetic energy is being imparted to the water Show Answer

Q459) Consider a rubber ball freely falling from a height h = 4.9 m onto a horizontal elastic plate. Assume that
the duration of collision is negligible and the collision with the plate is totally elastic.
Then the velocity as a function of time and the height as a function of time will be Show Answer

Q460) In an explosion a body breaks up into two pieces of unequal masses. In this Show Answer

Q461) A lorry and a car moving with the same K.E. are brought to rest by applying the same retarding force, then Show Answer

Q462) For a system to follow the law of conservation of linear momentum during a collision , the condition is
Total external force acting on the system is zero.
Total external force acting on the system finite and time of collision is negligible.
Total internal force acting on the system is zero. Show Answer

Q463) A horizontal force of 5N is required to maintain a velocity of 2 m/s for a block of 10 kg mass sliding over a
rough surface. The work done by this force in one minute is Show Answer

Q464) Consider the following statements A and B and identify the correct answer
III. In an elastic collision, if a body suffers a head on collision with another of same mass at rest, the first
body comes to rest while the other starts moving with the velocity of the first one
IV. Two bodies of equal mass suffering a head on elastic collision merely exchange their velocities. Show Answer

Q465) A pump motor is used to deliver water at a certain rate from s given pipe. To obtain twice as much water
from the same pipe in the same time, power of the motor has to be increased to Show Answer

Q466) A force of 5 N moves the particle through a distance of 10 m. If 25 J of work is performed, then the angle
between the force and the direction of motion is Show Answer

Q467) A uniform chain of length 2 m is kept on a table such that a length of 60 cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table? Show Answer

Q468) A body moving with velocity v has momentum and kinetic energy numerically equal. What is the value of v Show Answer

Q469) When a spring is extended by 2 cm energy stored is 100 J. When extended by further 2 cm, the energy increases by Show Answer

Q470) Two springs of spring constants 1500 N/m and 3000 N/m respectively are stretched with the same force. They will have potential energy in the ratio Show Answer

Q471) A neutron makes a head-on elastic collision with a stationary deuteron. The fractional energy loss of the neutron in the collision is Show Answer

Q472) Two bodies of masses 0.1 kg and 0.4 kg move towards each other with the velocities 1 m/s and 0.1 m/s respectively, After collision they stick together. In 10 sec the combined mass travels Show Answer

Q473) The kinetic energy of a body is increased by 300%. What is the percentage increase in the momentum of the body? Show Answer

Q474) The area of the acceleration-displacement curve of a body gives Show Answer

Q475) A neutron travelling with a velocity v and K.E. E collides perfectly elastically head on with the nucleus of an atom of mass number A at rest. The fraction of total energy retained by neutron is Show Answer

Q476) A body of mass 2kg makes an elastic collision with another body at rest and continues to move in the original direction with one fourth of its original speed. The mass of the second body which collides with the first body is Show Answer

Q477) A running man has half the kinetic energy of that of a boy of half of his mass. The man speeds up by 1m/s so as to have same K.E.. as that of the boy. The original speed of the man will be Show Answer

Q478) A long spring is stretched by 2 cm and its potential energy is U. If the spring is stretched by 10 cm; its
potential energy will be Show Answer

Q479) Two balls of masses 2 g and 6 g are moving with KE in the ratio of 3:1. What is the ratio of their linear
momenta? Show Answer

Q480) A box is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t is proportional to Show Answer

Q481) In elastic collision Show Answer

Q482) From a waterfall, water is falling down at the rate of 100 kg/s on the blades of turbine. If the height of the ball is 100 m, then the power delivered to the turbine is approximately equal to Show Answer

Q483) A 60 kg man runs up a staircase in 12 seconds while a 50 kg man runs up the same staircase in 11 seconds. The ratio of the rate of doing their work is Show Answer

Q484) A body of mass 4 kg moving with velocity 12 m/s collides with another body of mass 6 kg at rest. If two bodies stick together after collision, then the loss of kinetic energy of system is Show Answer

Q485) A man starts walking from a point on the surface of earth (assumed smooth) and reaches diagonally opposite point. What is the work done by him Show Answer

Q486) A light and a heavy body have equal momenta. Which one has greater K.E. Show Answer

Q487) A ball hits the floor and rebounds after inelastic collision. In this case Show Answer

Q488) If a body looses half of its velocity on penetrating 3 cm in a wooden block, then how much will it penetrate
more before coming to rest Show Answer

Q489) Under the action of a force F=Cx, the position of a body changes from 0 to x.The work done is Show Answer

Q490) A block of mass m at the end of the string is whirled round a vertical circle of radius r. The critical speed of
the block at the top of the swing is Show Answer

Q491) A body of mass m having an initial velocity v, makes head on collision with a stationary body of mass M. After the collision, the body of mass m comes to rest and only the body having mass M moves. This will happen only when Show Answer

Q492) A rifle bullet loses 1/20th of its velocity in passing through a plank. The least number of such planks required just to stop the bullet is Show Answer

Q493) The diagrams represent the potential energy U of a function of the inter-atomic distance r. Which diagram corresponds to stable molecules found in nature Show Answer

Q494) A force of 5 N acts on a 15 kg body initially at rest. The work done by the force during the first second of motion of the body is Show Answer

Q495) A body at rest explodes into two equal parts. Then, Show Answer

Q496) A particle is released from a height S.At certain height its kinetic energy is three times its potential energy .The height and speed of the particle at that instant are respectively Show Answer

Q497) An athlete in the Olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to
be in the range Show Answer

Q498) A body projected vertically from the earth reaches a height equal to earth’s radius before returning to the
earth. The power exerted by the gravitational force is greatest Show Answer

Q499) A bullet hits and gets embedded in a solid block resting on a horizontal frictionless table. What is
conserved Show Answer

Q500) mass of M kg is suspended by a weightless string. The horizontal force that is required to displace it until the string makes an angle of 45° with the initial vertical direction is Show Answer

Q501) In the non-relativistic regime, if the momentum, is increased by 100%, the percentage increase in kinetic energy is Show Answer

Q502) An ideal spring with spring constant k is hung from the ceiling and a block of mass M is attached to its lower end. The mass is released with the spring initially unstretched. Then the maximum extension in the spring is Show Answer

Q503) Two springs A and B are stretched by applying forces of equal magnitudes at the four ends. If spring constant of A is 2 times greater than that of spring B, and the energy stored in A is E, that in B is Show Answer

Q504) A spring with spring constant k when stretched through 1 cm, the potential energy is U. If it is stretched by 4 cm. The potential energy will be Show Answer

Q505) Two balls at same temperature collide. What is conserved Show Answer

Q506) A body moving with velocity v has momentum and kinetic energy numerically equal. What is the value of v? Show Answer

Q507) The force constant of a weightless spring is 16 N/m. A body of mass 1.0 kg suspended from it is pulled down through 5 cm and then released. The maximum kinetic energy of the system (spring + body) will be Show Answer

Q508) A plate of mass m, length b and breadth a is initially lying on a horizontal floor with length parallel to the floor and breadth perpendicular to the floor. The work done to erect it on its breadth is Show Answer

Q509) A 16 kg block moving on a frictionless horizontal surface with a velocity of 4 m/s compresses an ideal spring and comes to rest. If the force constant of the spring be 100 N/m, then the spring is compressed by Show Answer

Q510) A nucleus at rest splits into two nuclear parts having same density and radii in the ratio 1:2. Their velocities are in the ratio Show Answer

Q511) The power of a water jet flowing through an orifice of radius r with velocity v is Show Answer

Q512) If two balls each of mass 0.06 kg moving in opposite directions with speed 4 m/s collide and rebound with the same speed, then the impulse imparted to each ball due to other is Show Answer

Q513) A one kilowatt motor is used to pump water from a well 10 m deep. The quantity of water pumped out per
second is nearly Show Answer

Q514) The potential energy of a system increases if work is done Show Answer

Q515) If a skater of weight 3 kg has initial speed 32 m/s and second one of weight 4 kg has 5 m/s. After collision,
they have speed (couple) 5 m/s. Then the loss in K.E. is Show Answer

Q516) The area under the displacement-force curve gives Show Answer

Q517) The work done against gravity in taking 10 kg mass at 1m height in 1 sec will be Show Answer

Q518) The power of pump, which can pump 200 kg of water to a height of 50 m in 10 sec, will be Show Answer

Q519) A ball moving with speed v hits another identical ball at rest. The two balls stick together after collision. If
specific heat of the material of the balls is S, the temperature rise resulting from the collision is Show Answer

Q520) According to work-energy theorem, the work done by the net force on a particle is equal to the change in
its Show Answer

Q521) A body is moved along a straight line by machine delivering a constant power. The distance moved by the
body in time t is proportional to Show Answer

Q522) A ball is dropped from height 10 m. Ball is embedded in sand 1 m and stops, then Show Answer

Q523) A 50 kg man with 20 kg load on his head climbs up 20 steps of 0.25m height each. The work done in
climbing is Show Answer

Q524) Stopping distance of a moving vehicle is directly proportional to Show Answer

Q525) A spring of 40 mm long is stretched by the application of a force. If 10 N force required to stretch the spring through 1 mm, then work done in stretching the spring through 40 mm Show Answer

Q526) A ball is allowed to fall from a height of 10 m. If there is 40% loss of energy due to impact, then after one impact ball will go up to Show Answer

Q527) A man does a given amount of work in 10 sec. Another man does the same amount of work in 20 sec. The ratio of the output power of first man to the second man is Show Answer

Q528) The centripetal acceleration of a particle varies inversely with the square of the radius r of the circular path .The KE of this particle varies directly as Show Answer

Q529) A particle of mass ‘m’ and charge ‘q’ is accelerated through a potential difference of ‘V’ volt. Its energy is Show Answer

Q530) If F is the force required to keep a train moving at a constant speed v,the power required is Show Answer

Q531) Two masses of 1g and 4g are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is Show Answer

Q532) Consider the following two statements
1. Linear momentum of a system of particles is zero
2. Kinetic energy of a system of particles is zero,
Then Show Answer

Q533) Which of the following is not a perfectly inelastic collision Show Answer

Q534) A body is acted upon by a force, which is inversely proportional to the distance covered (x). The work done will be proportional to Show Answer

Q535) Which of the following is a scalar quantity Show Answer

Q536) A car of mass ‘m’ is driven with acceleration ‘a’ along a straight level road against a constant external resistive force ‘R’. When the velocity of the car is ‘V’, the rate at which the engine of the car is doing work will be Show Answer

Q537) An electric immersion heater of 1.08 kW is immersed in water. After the water has reached a temperature of 100℃, how much time will be required to produce 100 g of steam Show Answer

Q538) If a shell fired from a cannon ,explodes in mid air, then Show Answer

Q539) The height of the dam, in a hydroelectric power station is 10 m. In order to generate 1 MW of electric power,
The mass of water (in kg) that must fall per second on the blades of the turbines is Show Answer

Q540) A ball is dropped from a height of 20 cm. Ball rebounds to a height of 10 cm. What is the loss of energy? Show Answer

Q541) A person holds a bucket of weight 60 N. He walks 7m along the horizontal path and then climbs up a vertical distance of 5 m. The work done by the man is Show Answer

Q542) A vertical spring with force constant k is fixed on a table .A ball of mass m at a height h above the free upper end of the spring falls vertically on the spring, so that the spring is compressed by a distance d. The net work done in the process is Show Answer

Q543) A ball of mass m moves with speed v and strikes a wall having infinite mass and it returns with same speed then the work done by the ball on the wall is Show Answer

Q544) A bullet of mass m moving with velocity v strikes a suspended wooden block of mass M. If the block rises to a height h, the initial velocity of the block will be Show Answer

Q545) A particle P moving with speed v undergoes a head–on elastic collision with another particle Q of identical mass but at rest. After the collision Show Answer

Q546) A motor is used to deliver water at a certain rate through a given horizontal pipe. To deliver n-times the water through the same time the power of the motor must be increased as follows Show Answer

Q547) The kinetic energy of a body becomes four times its initial value. The new momentum will be Show Answer

Q548) An apple gives 21 kJ energy to a boy. How much height he can climb by using this energy if his efficiency is 28% (mass of boy = 40 kg)
Show Answer

Q549) A sphere collides with another sphere of identical mass. After collision, the two spheres move. The
collision is inelastic. Then the angle between the directions of the two spheres is Show Answer

Q550) A ball of mass 10 kg is moving with a velocity of 10 m/s. It strikes another ball of mass 5 kg which is
moving in the same direction with a velocity of 4 m/s. If the collision is elastic , their velocities after the
collision will be, respectively Show Answer

Q551) Two identical blocks A and B, each of mass ‘m’ resting on smooth floor are connected by a light spring of
natural length L and spring constant K, with the spring at its natural length. A third identical block ‘C’
(mass m) moving with a speed v along the line joining A and B collides with A. The maximum compression
in the spring is Show Answer

Q552) A body moves a distance of 5m along a straight line under the action of a force of 10 N. If the work done is
25 J, then the angel which the force makes with the direction of motion of the body is Show Answer

Q553) You lift a heavy book from the floor of the room and keep it in the book–shelf having a height 2 m. In this
process you take 5 seconds. The work done by you will depend upon Show Answer

Q554) A body of mass M is dropped from a height h on a sand floor. If the body penetrates x cm into the sand, the
average resistance offered by the sand to the body is Show Answer

Q555) The potential energy of a weight less spring compressed by a distance a is proportional to Show Answer

Q556) In the stable equilibrium position, a body has Show Answer

Q557) A body falling from a height of 10m rebounds from hard floor. If it loses 20% energy in the impact, then coefficient of restitution is Show Answer

Q558) Which of the following is a unit of energy Show Answer

Q559) A body of mass 0.1 kg moving with a velocity of 10 m/s hits a spring (fixed at the other end) of force constant 1000 N/m and comes to rest after compressing the spring. The compression of the spring is Show Answer

Q560) The coefficient of restitution e for a perfectly elastic collision is Show Answer

Q561) To the free end of spring hanging from a rigid support, a block of mass m is hung and slowly allowed to come to its equilibrium position. Then stretching in the spring is d. if the same block is attached to the same spring and allowed to fall suddenly, the amount of stretching is (force constant ,k) Show Answer

Q562) If a long spring is stretched by 0.02 m, its potential energy is U. If the spring is stretched by 0.1 m, then its
potential energy will be Show Answer

Q563) A ball of mass m moving with velocity V, makes a head on elastic collision with a ball of the same mass
moving with velocity 2V towards it. Taking direction of V as positive velocities of the two balls after
collision are Show Answer

Q564) The power supplied by a force acting on a particle moving in a straight line is constant. The velocity of the
particle varies with the displacement x as Show Answer

Q565) Two masses of 1 g and 4g are moving with equal kinetic energies. The ratio of the magnitudes of their
linear momenta is Show Answer

Q566) A particle of mass 100g is thrown vertically upwards with a speed of 5m/s. The work done by the force of
gravity during the time the particle goes up is Show Answer

Q567) The potential energy of a certain spring when stretched through a distance s is 10 J .The amount of work
done (in joule)that must be done on this spring to stretch it through an additional distance s, will be Show Answer

Q568) A body moves a distance of 10 m along a straight line under the action of a force of 5 N. If the work done is
25 joules, the angle which the force makes with the direction of motion of the body is Show Answer

Q569) A body of mass m is rest. Another body of same mass moving with velocity v makes head on elastic
collision with the first body. After collision the first body starts to moves with velocity Show Answer

Q570) A mass of 20 kg moving with a speed of 10 m/s collides with another stationary mass of 5 kg As a result of the collision, the two masses stick together. The kinetic energy of the composite mass will be Show Answer

Q571) A body of mass m kg is lifted by a man to a height of one metre in 30 sec. Another man lifts the same mass to the same height in 60 sec. The work done by them are in the ratio Show Answer

Q572) The kinetic energy acquired by a body of mass m in travelling some distance s, starting from rest under the action of a constant force, is directly proportional to Show Answer

Q573) Which of the following is not a conservative force Show Answer

Q574) A chain of mass M is placed on a smooth table with 1/3 of its length L hanging over the edge. The work done in pulling the chain back to the table is Show Answer

Q575) A motor drives a body along a straight line with a constant force. The power P developed by the motor
must vary with time t as shown in figure Show Answer

Q576) A uniform chain of length 2m is kept on a table such that a length of 60 cm hangs freely from the edge of
the table. The total mass of the chain is 4kg. What is the work done in pulling the entire chain on the table Show Answer

Q577) Which among the following, is a form of energy Show Answer

Q578) If the momentum of a body is increased by 100%, then the percentage increase in the kinetic energy is Show Answer

Q579) A rod AB of mass 10kg and length 4m rests on a horizontal floor with end A fixed so as to rotate it in
vertical plane about perpendicular axis passing through A. If the work done on the rod is 100 J, the height
to which the end B be raised vertically above the floor is Show Answer

Q580) A particle of mass m moving eastward with a speed v collides with another particle of the same mass
moving northward with the same speed v. The two particles coalesce on collision. The new particle of
mass 2m will move in the north-easterly direction with a velocity Show Answer

Q581) A ball hits a vertical wall horizontally at 10 m/s bounces back at 10 m/s Show Answer

Q582) Two bodies moving towards each other collide and move away in opposite directions. There is some rise
in temperature of bodies because a part of the kinetic energy is converted into Show Answer

Q583) A lead ball strikes a wall and falls down, a tennis ball having the same mass and velocity strikes the wall
and bounces back. Check the correct statement Show Answer

Q584) A bomb of mass 9 kg explodes into 2 pieces of mass 3kg and 6kg. The velocity of mass 3kg is 1.6 m/s, the
K.E. of mass 6kg is Show Answer

Q585) If force and displacement of particle in direction of force are doubled. Work would be Show Answer

Q586) A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic
energy for any displacement x is proportional to Show Answer

Q587) If the kinetic energy of a body increases by 0.1%, the percent increase of its momentum will be Show Answer

Q588) The slope of the kinetic energy versus position vector gives the rate of change of Show Answer

Q589) A spring gun of spring constant 90 N/cm is compressed 12 cm by a ball of mass 16 g. If the trigger is
pulled, the velocity of the ball is Show Answer

Q590) A block of mass 10 kg slides down a rough slope which is inclined at 45° to the horizontal. The coefficient
of sliding friction is 0.30. When the block has slide 5 m, the work done on the block by the force of friction
is nearly Show Answer

Q591) A car of mass m is driven with an acceleration a along a straight level road against a constant external
resistive force R. When the velocity of the car is v, the rate at which engine of the car is doing work, will be Show Answer

Q592) An open knife edge of mass ‘m’ is dropped from a height ‘h’ on a wooden floor. If the blade penetrates upto
the depth ‘d’ into the wood, the average resistance offered by the wood edge is Show Answer

Q593) A bomb of mass 3m kg explodes into two pieces of mass m kg and 2m kg. If the velocity of m kg mass is
16 m/s, the total kinetic energy released in the explosion is Show Answer

Q594) A body at rest breaks up into 3 parts. If 2 parts having equal masses fly off perpendicularly each after with
a velocity of 12 m/s, then the velocity of the third part which has 3 times mass of each part is Show Answer

Q595) A dam is situated at a height of 550 m above sea level and supplies water to a power house which is at a
height of 50 m above sea level. 2000 kg of water passes through the turbines per second. What would be
the maximum electrical power output of the power house if the whole system were 80% efficient? Show Answer

Q596) A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of
the particle, the motion of the particle takes place in a plane. It follows that Show Answer

Q597) A spring when stretched by 2 mm its potential energy becomes 4 J. If it is stretched by 10 mm, its potential
energy is equal to Show Answer

Q598) A ball whose kinetic energy is E, is projected at an angle 45° to the horizontal. The kinetic energy of the
ball at the highest point of its flight will be Show Answer

Q599) A body of mass 10 kg at rest is acted upon simultaneously by two forces 4 N and 3 N at right angles to
each other. The kinetic energy of the body at the end of 10 sec is Show Answer

Q600) If the K.E. of a particle is doubled, then its momentum will Show Answer

Q601) When a body moves with some friction on a surface Show Answer

Q602) An ice cream has a marked value of 700 kcal. How many kilowatt - hour of energy will it deliver to the body as it is digested Show Answer

Q603) Two bodies with kinetic energies in the ratio of 4∶1 are moving with equal linear momentum. The ratio of their masses is Show Answer

Q604) If a man increase his speed by 2 m/s, his K.E. is doubled, the original speed of the man is Show Answer

Q605) The momentum of a body increases by 20%. The percentage increase in its kinetic energy is Show Answer

Q606) A big ball of mass M, moving with velocity u strikes a small ball of mass m, which is at rest. Finally small ball obtains velocity u and big ball v. Then what is the value of v Show Answer

Q607) In which of the following cases, can the work done increase the potential energy? Show Answer

Q608) A rock of mass m is dropped to the ground from a height h. A second rock with mass 2m is dropped from the same height. When second rock strikes the ground, what is its kinetic energy? Show Answer

Q609) A bomb of 12 kg divides in two parts whose ratio of masses is 1∶3. If kinetic energy of smaller part is 216 J, then momentum of bigger part in kg-m/sec will be Show Answer

Q610) An elastic ball is dropped from a height h and it rebounds many times from the floor .If the coefficient of restitution is e, the times interval between the second and the third impact, is Show Answer

Q611) A body is moving with velocity v, breaks up into two equal parts. One of the part retraces back with velocity v. Then the velocity of the other part is Show Answer

Q612) The energy associated with one gram of mass is Show Answer

Q613) Identify the false statement from the following Show Answer

Q614) A shell initially at rest explodes into two pieces of equal mass, then the two pieces will Show Answer

Q615) The quantity that is not conserved in an inelastic collision is Show Answer

Q616) Two masses of 1 g and 4 g have same kinetic energy what is the ratio of their momenta? Show Answer

Q617) A car of mass 1250 kg is moving at 30 m/s. Its engine delivers 30 kW while resistive force due to surface is 750 N. What max acceleration can be given in the car Show Answer

Q618) At high altitude, a body explodes at rest into two equal fragments with one fragment receiving horizontal velocity of 10 m/s. Time taken by the two radius vectors connecting point of explosion to fragments to make 90° is Show Answer

Q619) A particle of mass m is being circulated on a vertical circle of radius r. If the speed of particle at the highest
point be v, then Show Answer

Q620) A particle is placed at the origin and force F = kx is acting on it (where k is positive constant ).if u(0) =
0.the graph u(x) versus x will (where u is potential energy function) Show Answer

Q621) A time t=0 s Particle starts moving along the x-axis. If its kinetic energy increases uniformly with time t,
the net force acting on it must be proportional to Show Answer

Q622) A stone tied to a string of length L is whirled in a vertical circle with the other end of the string at the
centre. At a certain instant of time, the stone is at its lowest position and has a speed u. The magnitude of
the change in its velocity as it reaches a position where the string is horizontal is Show Answer

Q623) A sphere of mass m, moving with velocity V, enters a hanging bag of sand and stops. If the mass of the bag is M and it is raised by height h, then the velocity of the sphere was Show Answer

Q624) A particle of mass m moving with velocity v strikes a stationary particle of mass 2m and sticks to it. The speed of the system will be Show Answer

Q625) The kinetic energy of a body of mass 3kg and momentum 2 Ns is Show Answer

Q626) A particle of mass m at rest is acted upon by a force F for a time t. Its kinetic energy after an interval t is Show Answer

Q627) A body of mass M is hung by a long thread and a bullet of mass m hits it horizontally with a velocity v and gets embedded in the body. Then for the body and the bullet system Show Answer

Q628) The spring extends by x on loading, then energy stored by the spring is :
(If T is the tension in spring and k is spring constant) Show Answer

Q629) A particle of mass M starting from rest undergoes uniform acceleration. If the speed acquired in time T is V, the power delivered to the particle is Show Answer

Q630) A mass of 0.5 kg moving with a speed of 1.5 m/s on a horizontal smooth surface, collides with a nearly weightless spring of force constant k=50 N/m. The maximum compression of the spring would be Show Answer

Q631) A car of mass 1000 kg accelerates uniformly from rest to a velocity of 54 km/hour in 5s. The average power of the engine during this period in watts is (neglect friction) Show Answer

Q632) A ball is released from the top of a tower. The ratio of work done by force of gravity in first, Second and
third second of the motion of the ball is Show Answer

Q633) A uniform force of 4 N acts on a body of mass 10 kg for a distance of 2.0 m. The kinetic energy acquired by
the body is Show Answer

Q634) A spherical ball of mass 20 kg is stationary at the top of a hill of height 100 m. It rolls down a smooth
surface to the ground, then climbs up another hill of height 30 m and height of 20 m above the ground. The
velocity attained by the ball is Show Answer

Q635) A glass ball is dropped from height 10 m. If there is 20% loss of energy due to impact, then after one
impact, the ball will be upto Show Answer

Q636) Two bodies are having kinetic energies in the ratio 16:9. If they have same linear momentum, the ratio of their masses respectively is Show Answer

Q637) Given below are two statements :
Statement I A truck and a car moving with the same kinetic energy are brought to rest by applying breaks which provide equal retarding forces. Both come to rest in equal distance.
Statement II A car moving towards east takes a turn and moves towards north, the speed remains unchanged. The acceleration of the car is zero. In the light of above statements, choose the most appropriate answer from the options given below. Show Answer

Q638) For a body projected at an angle with the horizontal from the ground. Choose the correct statement. Show Answer

Q639) Identify the correct statements from the following A. Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket is negative. B. Work done by gravitational force in lifting a bucket out of a well by a rope tied to the bucket is negative.
WORK, ENERGY AND POWER
C. Work done by friction on a body sliding down an inclined plane is positive.
D. Work done by an applied force on a body moving on a rough horizontal plane with uniform velocity in
zero.
E. Work done by the air resistance on an oscillating pendulum is negative.
Choose the correct answer from the options given below Show Answer

Q640) A stone is projected at angle 30° to the horizontal. The ratio of kinetic energy of the stone at point of projection to its kinetic energy at the highest point of flight will be Show Answer

Q641) If momentum of a body is increased by 20%, then its kinetic energy increases by
Show Answer

Q642) A ball is projected with kinetic energy E, at an angle of 60° to the horizontal. The kinetic energy of this ball at the highest point of its flight will become Show Answer

Q643) A body of mass 8 kg and another of mass 2 kg are moving with equal kinetic energy. The ratio of their respective momenta will be Show Answer

Q644) A block moving horizontally on a smooth surface with a speed of 40 m/s splits into two parts with masses in the ratio of 1:2. If the smaller part moves at 60 m/s in the same direction, then the fractional change in kinetic energy is Show Answer

Q645) If the kinetic energy of a moving body becomes four times of its initial kinetic energy, then the percentage change in its momentum will be Show Answer

Q646) An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range Show Answer

Q647) A 2 kg block slides on a horizontal floor with a speed of 4 m/s. It strikes a uncompressed spring and compresses it till the block is motionless. The kinetic friction force is 15 N and spring constant is 10000 N/m. The spring compresses by Show Answer

Q648) A spherical ball of mass 20 kg is stationary at the top of a hill of height 100 m. It rolls down a smooth surface to the ground, then climbs up another hill of height 30 m and finally rolls down to a horizontal base at a height of 20 m above the ground. The velocity attained by the ball is Show Answer

Q649) A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement x is proportional to Show Answer

Q650) A uniform chain of length 2 m is kept on a table such that a length of 60 cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table? Show Answer

Q651) Consider the following two statements.
I. Linear momentum of a system of particles is zero. II. Kinetic energy of a system of particles is zero. Then, Show Answer

Q652) A spring of force constant 800 N/m has an extension of 5 cm. The work done in extending it from 5 cm to 15 cm is Show Answer

Q653) A ball whose kinetic energy is E, is projected at an angle of 45° to the horizontal. The kinetic energy the ball at the highest point of its flight will be Show Answer

Q654) The momentum of a body is increased by 50%. The percentage increase in the kinetic energy of the body is..........%. Show Answer

Q655) To maintain a speed of 80 km/h by a bus of mass 500 kg on a plane rough road for 4 km distance, the work done by the engine of the bus will be ......... kJ. [The coefficient of friction between tyre of bus and road is 0.04] Show Answer

Q656) A block of mass 10 kg is moving along X-axis under the action of force F = 5x N. The work done by the force in moving the block from x =2m to 4 m will be ............ J Show Answer

Q657) A car accelerates from rest to u m/s. The energy spent in this process is E J. The energy required to accelerate the car from u m/s to 2u m/s is nE J. The value of n is Show Answer

Q658) A spherical body of mass 2 kg starting from rest acquires a kinetic energy of 10000 J at the end of 5th seconds. The force acted on the body is........ N. Show Answer

Q659) A uniform chain of 6 m length is placed on a table, such that a part of its length is hanging over the edge of the table. The system is at rest. The coefficient of static friction between the chain and the surface of the table is 0.5, the maximum length of the chain hanging from the table is... m. Show Answer

Q660) Two particles having masses 4 g and 16 g respectively are moving with equal kinetic energies. The ratio of the magnitudes of their linear momentum is n : 2. The value of n will be .... Show Answer

Q661) A stone of mass m, tied to a string is being whirled in a vertical circle with a uniform speed. The tension in the string is Show Answer

Q662) A time dependent force F=6t acts on a particle of mass 1 kg. If the particle starts from rest, the work done by the force during the first 1 s will be Show Answer

Q663) A mass of M kg is suspended by a weightless string. The horizontal force that is required to displace it until the string makes an angle of 45° with the initial vertical direction is Show Answer

Q664) A bullet fired into a fixed target loses half of its velocity after penetrating 3 cm. How much further it. will penetrate before coming to rest, assuming that it faces constant resistance to motion? Show Answer

Q665) A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle. The motion of the particle takes place in a plane, it follows that Show Answer

Q666) An automobile of mass m accelerates starting from origin and initially at rest, while the engine supplies constant power P. The position is given as a function of time by Show Answer

Q667) Two billiard balls of mass 0.05 kg each moving in collide and opposite directions with 10 ms rebound with the same speed. If the time duration of contact is t=0.005 s, then what is the force exerted on the ball due to each other? Show Answer

Q668) What percentage of kinetic energy of a moving particle is transferred to a stationary particle when it strikes the stationary particle of 5 times its mass? (Assume the collision to be head-on elastic collision) Show Answer

Q669) Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion (A) Body P having mass M moving with speed u has head-on collision elastically with another body Q having mass m initially at rest. If m << M, body Q will have a maximum speed equal to 2u after collision.
Reason (R) During elastic collision, the momentum and kinetic energy are both conserved. In the light of the above statements, choose the most appropriate answer from the options given below. Show Answer

Q670) A body of mass 2 kg makes an elastic collision with a second body at rest and continues to move in the original direction but with one-fourth of its original speed. What is the mass of the second body? [ Show Answer

Q671) In a collinear collision, a particle with an initial speed o strikes a stationary particle of the same mass. If the final total kinetic energy is 50% greater than the original kinetic energy, the magnitude of the relative velocity between the two particles after collision, is Show Answer

Q672) A proton of mass m collides elastically with a particle of unknown mass at rest. After the collision, the proton and the unknown particle are seen moving at an angle of 90° with respect to each other. The mass of unknown particle is Show Answer

Q673) A particle of mass m moving in the x-direction with speed 2v is hit by another particle of mass 2m moving in the y-direction with speed v. If the collision is perfectly inelastic, the percentage loss in the energy during the collision is close to Show Answer

Q674) Statement I Two particles moving in the same
direction do not lose all their energy in a completely Hinelastic collision.
Statement II Principle of conservation of momentum holds true for all kinds of collisions. Show Answer

Q675) A ball with a speed of 9 m/s collides with another identical ball at rest. After the collision, the direction of each ball makes an angle of 30° with the original direction. The ratio of velocities of the balls after collision is x: y, where x is ..... Show Answer