Practice Test


1) The property of a body, by virtue of which it tends to regain its original shape and size when the applied force is removed, is known as


2) The SI unit of stress is Pascal, its dimensional formula is


3) If a body subject to stress-strain tests is taken slightly beyond the elastic limit and then the load is removed.


4) Substances like tissues of aorta, rubber etc. which can be stretched to cause large strains are called


5) The pressure on a swimmer 10 m below the surface of a lake is


6) In a car lift, compressed air exerts a force F, an a small piston having a radius of 5.0 cm. This pressure is transmitted to a second piston of radius 15 cm. If the mass of the car to be lifted is 1350 kg, calculate F,


7) What is the specific gravity of spirit?


8) If 15 cm of water and spirit each are further poured into the respective arms of the tube, what is the difference in the levels of mercury in the two arms? (Specific gravity of mercury = 13.6 )


9) The possible value of Poisson's ratio is


10) What is the Young's modulus of elasticity for a perfectly rigid body?


11) The dimensions of four wires of the same material are given below. In which wire the increaase in length will be maximum?


12) A wire extends by 1 mm when a force is applied. Double the force is applied to another wire of same material and length but half the radius of cross-section. The elongation of the wire in mm will be


13) A ball floats on the surface of water in a container exposed to the atmosphere. When the container is covered and the air is partially removed, then the ball


14) Statement 1 : A block floats in water partially immersed. When whole system is given constant upward acceleration then volume of block inside water remains unchanged.
Statement 2 : Net force on block in both case is zero, ignoring pseudo forces (if any)


15) Statement 1 : If a barometer is accelerated upwards, the level of mercury in the tube of barometer will decrease.
Statement 2 : The effective value of acceleration due to gravity will increase, so upthrust will increase.


16) The pressure due to liquid at the bottom of vessel is (ignore any effect of the atomsphere)


17) If a sphere of mass M is dropped into the cylindrical vessel and if sphere floats in the vessel then pressure at the bottom of vessel is (ignore any effect of the atmosphere) (where A is cross-sectional area of bottom)


18) If the vessel starts falling vertically downward freely under gravity, the pressure due to liquid column at the bottom of vessel will be


19) The human lungs can operate against a pressure difference of up-to 0.6 atmosphere. A diver uses a snorkel (long tube) for breathing. How far below the water level can he swim?


20) Statement 1 : A solid sphere and a hollow sphere of same material are floating in a liquid. Radius of both the spheres are same. Percentage of volume immersed of both the sphere will be same.
Statement 2 : Up thrust is based on volume of liquid displaced. It has nothing to do whether the body is solid or hollow.


21) The increase in length is l of a wire of length L by the longitudinal stress. Then the stress is proportional to


22) The ratio of the lengths of two wires A and B of same material is 1 : 2 and the ratio of their diameter is 2 : 1. They are stretched by the same force, and then the ratio of increase in length will be


23) A beam of metal supported at the two ends is loaded at the centre. The depression at the centre is proportional to


24) When a certain weight is suspended from a long uniform wire, its length increases by one cm. If the same weight is suspended from another wire of the same material and length but having a diameter half of the first one then the increase in length will be


25) Hook's law defines


26) A wire is loaded by 6 kg at its one end; the increase in length is 12 mm. If the radius of the wire is doubled and all other magnitudes are unchanged, then increase in length will be


27) The material which practically does not show elastic after effect is


28) If the temperature increases, the modulus of elasticity


29) A force F is needed to break a copper wire having radius R. The force needed to break a copper wire of radius 2R will be


30) If x longitudinal strain is produced in a wire of Young's modulus y, then energy stored in the material of the wire per unit volume is


31) In a wire of length L, the increase in its length is l. If the length is reduced to half, the increase in its length will be


32) A and B are two wires. The radius of A is twice that of B. They are stretched by the some load. Then the stress on B is


33) If the length of a wire is reduced to half, then it can hold the ......... load


34) The spring balance does not read properly after its long use, because


35) Two wires of equal lengths are made of the same material. Wire A has a diameter that is twice as that of wire B. If identical weights are suspended from the ends of these wires, the increase in length is


36) Why the spring is made up of steel in comparison of copper?


37) Increase in length of a wire is 1 mm when suspended by a weight. If the same weight is suspended on a wire of double its length and double its radius, the increase in length will be


38) Two wires of copper having the length in the ratio 4 : 1 and their radii ratio as 1 : 4 are stretched by the same force. The ratio of longitudinal strain in the two will be


39) If a load of 9 kg is suspended on a wire, the increase in length is 4.5 mm. The force constant of the wire is


40) The length of an iron wire is L and area of cross-section is A. The increase in length is l on applying the force F on its two ends. Which of the statement is correct?


41) The ratio of diameters of two wires of same material is n : 1. The length of wires are 4 m each. On applying the same load, the increase in length of thin wire will be


42) A steel wire is stretched with a definite load. If the Young's modulus of the wire is Y. For decreasing the value of Y


43) Two identical wires of rubber and iron are stretched by the same weight, then the number of atoms in the iron wire will be


44) The force constant of a wire does not depend on


45) The elasticity of invar


46) After effects of elasticity are maximum for


47) In suspended type moving coil galvanometer, quartz suspension is used because


48) The quality of the material which opposes the change in shape, volume or length is called


49) The longitudinal strain is only possible in


50) If the density of the material increases, the value of Young's modulus


51) The elastic limit for a gas


52) If Young's modulus for a material is zero, then the state of material should be


53) Liquids have no Poisson's ratio, because


54) A wire of length L and radius r is rigidly fixed at one end. On stretching the other end of the wire with a force F, the increase in its length is l. If another wire of same material but of length 2L and radius 2r is stretched with a force of 2F, the increase in its length will be


55) Which of the following statements is correct?


56) Which one of the following substances possesses the highest elasticity?


57) Which one of the following quantities does not have the unit of force per unit area?


58) A copper wire and a steel wire of the same diameter and length are connected end to end and a force is applied, which stretches their combined length by 1 cm. The two wires will have


59) When a weight of 10 kg is suspended from a copper wire of length 3 metres and diameter 0.4 mm, its length increases by 2.4 cm. If the diameter of the wire is doubled, then the extension in its length will be


60) Two wires 'A' and 'B' of the same material have radii in the ratio 2 : 1 and lengths in the ratio 4 : 1. The ratio of the normal forces required to produce the same change in the lengths of these two wires is


61) Density of rubber is d. A thick rubber cord of length L and cross-section area A undergoes elongation under its own weight on suspending it. This elongation is proportional to


62) A fixed volume of iron is drawn into a wire of length L. The extension x produced in this wire by a constant force F is proportional to


63) To keep constant time, watches are fitted with balance wheel made of


64) A wire is stretched by 0.01 m by a certain force F. Another wire of same material whose diameter and length are double to the original wire is stretched by the same force. Then its elongation will be


65) The extension of a wire by the application of load is 3 mm. The extension in a wire of the same material and length but half the radius by the same load is


66) In which case there is maximum extension in the wire, if same force is applied on each wire


67) If a spring is extended to length l, then according to Hook's law


68) Which of the following affects the elasticity of a substance?


69) In solids, inter-atomic forces are


70) A force F is applied on the wire of radius r and length L and change in the length of wire is l. If the same force F is applied on the wire of the same material and radius 2r and length 2L, Then the change in length of the other wire is


71) The modulus of elasticity is dimensionally equivalent to


72) Under elastic limit the stress is


73) When compared with solids and liquids, the gases have


74) A load W produces an extension of 1mm in a thread of radius r. Now if the load is made 4W and radius is made 2r all other things remaining same, the extension will become


75) The units of Young's modulus of elasticity are


76) When a uniform wire of radius r is stretched by a 2kg weight, the increase in its length is 2.00 mm. If the radius of the wire is r/2 and other conditions remain the same, the increase in its length is


77) Stress to strain ratio is equivalent to


78) Which is correct relation?


79) According to Hook's law of elasticity, if stress is increased, the ratio of stress to strain


80) A pan with set of weights is attached with a light spring. When disturbed, the mass-spring system oscillates with a time period of 0.6 s. When some additional weights are added then time period is 0.7s. The extension caused by the additional weights is approximately given by


81) A uniform plank of Young's modulus Y is moved over a smooth horizontal surface by a constant horizontal force F. The area of cross section of the plank is A. The compressive strain on the plank in the direction of the force is


82) The breaking stress of a wire depends upon


83) According to Hook's law force is proportional to


84) In the Young's experiment, if length of wire and radius both are doubled then the value of Y will become


85) Minimum and maximum values of Poisson's ratio for a metal lies between


86) A wire of diameter 1mm breaks under a tension of 1000 N. Another wire, of same material as that of the first one, but of diameter 2 mm breaks under a tension of


87) Young's modulus of perfectly rigid body material is


88) The value of Poisson's ratio lies between


89) The Poisson's ratio cannot have the value


90) There is no change in the volume of a wire due to change in its length on stretching. The Poisson's ratio of the material of the wire is


91) Four identical rods are stretched by same force. Maximum extension is produced in


92) The isothermal elasticity of a gas is equal to


93) The adiabatic elasticity of a gas is equal to


94) The only elastic modulus that applies to fluids is


95) The ratio of the adiabatic to isothermal elasticities of a triatomic gas is


96) The compressibility of a material is


97) In the three states of matter, the elastic coefficient can be


98) Bulk modulus was first defined by


99) A uniform cube is subjected to volume compression. If each side is decreased by 1%, then bulk strain is


100) A ball falling in a lake of depth 200 m shows 0.1% decreases in its volume at the bottom. What is the bulk modulus of the material of the ball


101) The isothermal bulk modulus of a gas at atmospheric pressure is


102) The bulk modulus of an ideal gas at constant temperature


103) The Bulk modulus for an incompressible liquid is


104) Modulus of rigidity of diamond is


105) The ratio of lengths of two rods A and B of same material is 1 : 2 and the ratio of their radii is 2 : 1, then the ratio of modulus of rigidity of A and B will be


106) Which statement is true for a metal?


107) Which of the following relations is true?


108) When a spiral spring is stretched by suspending a load on it, the strain produced is called


109) If the Young's modulus of the material is 3 times its modulus of rigidity, then its volume elasticity will be


110) Modulus of rigidity of a liquid


111) For a given material, the Young's modulus is 2.4 times that of rigidity modulus. Its Poisson's ratio is


112) A cube of aluminium of sides 0.1 m is subjected to a shearing force of 100 N. The top face of the cube is displaced through 0.02 cm with respect to the bottom face. The shearing strain would be


113) The reason for the change in shape of a regular body is


114) Mark the wrong statement


115) A 2 m long rod of radius 1 cm which is fixed from one end is given a twist of 0.8 radians. The shear strain developed will be


116) Shearing stress causes change in


117) If the potential energy of a spring is V on stretching it by 2 cm, then its potential energy when it is stretched by 10 cm will be


118) The work done in stretching an elastic wire per unit volume is or strain energy in a stretched string is


119) Calculate the work done, if a wire is loaded by 'Mg' weight and the increase in length is 'l'


120) Two wires of same diameter of the same material having the length l and 2l. If the force F is applied on each, the ratio of the work done in the two wires will be


121) A 5 metre long wire is fixed to the ceiling. A weight of 10 kg is hung at the lower end and is 1 metre above the floor. The wire was elongated by 1 mm. The energy stored in the wire due to stretching is


122) If the force constant of a wire is K, the work done in increasing the length of the wire by l is


123) If the tension on a wire is removed at once, then


124) When strain is produced in a body within elastic limit, its internal energy


125) When shearing force is applied on a body, then the elastic potential energy is stored in it. On removing the force, this energy


126) If one end of a wire is fixed with a rigid support and the other end is stretched by a force of 10 N, then the increase in length is 0.5 mm. The ratio of the energy of the wire and the work done in displacing it through 1.5 mm by the weight is


127) A wire is suspended by one end. At the other end a weight equivalent to 20 N force is applied. If the increase in length is 1.0 mm, the increase in energy of the wire will be


128) A wire is suspended by one end. At the other end a weight equivalent to 20 N force is applied. If the increase in length is 1.0 mm, the ratio of the increase in energy of the wire to the decrease in gravitational potential energy when load moves downwards by 1 mm, will be


129) The Young's modulus of a wire is Y. If the energy per unit volume is E, then the strain will be


130) The ratio of Young's modulus of the material of two wires is 2 : 3. If the same stress is applied on both, then the ratio of elastic energy per unit volume will be


131) If a spring extends by x on loading, then the energy stored by the spring is (if T is tension in the spring and k is spring constant)


132) On stretching a wire, the elastic energy stored per unit volume is


133) The elastic energy stored in a wire of Young's modulus Y is


134) When load of 5 kg is hung on a wire then extension of 3m takes place, then work done will be


135) A stretched rubber has


136) Which of the following is true for elastic potential energy density?


137) 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 1 mm. Then the elastic energy stored in the wire is


138) Wires A and B are made from the same material. A has twice the diameter and three times the length of B. If the elastic limits are not reached, when each is stretched by the same tension, the ratio of energy stored in A to that in B is


139) The extension in a string obeying Hooke's law is x. The speed of sound in the stretched string is v. If the extension in the string is increased to 1.5x, the speed of sound will be


140) There are two wires of same material and same length while the diameter of second wire is 2 times the diameter of first wire, then ratio of extension produced in the wires by applying same load will be


141) An elastic material of Young's modulus Y is subjected to a stress S. The elastic energy stored per unit volume of the material is


142) The part in which Hooke's law holds good is


143) In the above graph, point B indicates


144) In the above graph, point D indicates


145) Assertion : The stretching of a coil is determined by its shear modulus.
Reason : Shear modulus change only shape of a body keeping its dimensions unchanged.


146) Assertion : Spring balances show correct readings even after they had been used for a long time interval.
Reason : On using for long time, spring balances losses its elastic strength.


147) Assertion : Steel is more elastic than rubber.
Reason :Under given deforming force, steel is deformed less than rubber.


148) Assertion : Glassy solids have sharp melting point.
Reason : The bonds between the atoms of glassy solids get broken at the same temperature.


149) Assertion : A hollow shaft is found to be stronger than a solid shaft made of same material.
Reason : The torque required to produce a given twist in hollow cylinder is greater than that required to twist a solid cylinder of same size and material.


150) Assertion : Bulk modulus of elasticity (K) represents incompressibility of the material.
Reason : Bulk modulus of elasticity is proportional to change in pressure.


151) Assertion : Strain is a unitless quantity.
Reason : Strain is equivalent to force.


152) Assertion : The bridges declared unsafe after a long use.
Reason : Elastic strength of bridges losses with time.


153) Assertion : Two identical solid balls, one of ivory and the other of wet-clay are dropped from the same height on the floor. Both the balls will rise to same height after bouncing.
Reason : Ivory and wet-clay have same elasticity.


154) Assertion : Young’s modulus for a perfectly plastic body is zero.
Reason : For a perfectly plastic body, restoring force is zero.


155) Assertion : Identical springs of steel and copper are equally stretched. More work will be done on the steel spring.
Reason : Steel is more elastic than copper.


156) Assertion : Stress is the internal force per unit area of a body.
Reason : Rubber is less elastic than steel.


157) Two wires A and B of same length, same area of cross-section having the same Young's modulus are heated to the same range of temperature. If the coefficient of linear expansion of A is 3/2 times of that of wire B. The ratio of the forces produced in two wires will be


158) To break a wire of one meter length, minimum 40 kg wt. is required. Then the wire of the same material of double radius and 6 m length will require breaking weight


159) The increase in length on stretching a wire is 0.05%. If its Poisson's ratio is 0.4, then its diameter


160) If the breaking force for a given wire is F, then the breaking force of two wires of same magnitude will be


161) If the thickness of the wire is doubled, then the breaking force in the above question will be


162) The mass and length of a wire are M and L respectively. The density of the material of the wire is d. On applying the force F on the wire, the increase in length is l, and then the Young's modulus of the material of the wire will be