Practice Test


1) Newton's law of gravitation is applicable for:


2) Which of the following interactions is the weakest?


3) The weight of the body at the centre of earth is:


4) To what height the body is to be raised so that force of gravity on it is 1% of the value on the surface of earth? (Radius of earth is 6400 km)


5) The tidal waves in the sea are primarily due to the:


6) A body of mass 'm' taken from earth surface to a height equal to the radius of earth, the changes in its potential energy is (letters have usual meaning):


7) The weight of the body at earth's surface is W. At a depth half way to the centre of earth its weight will be (Density uniform):


8) If radius of earth shrinks by 2% (mass remaining same), how much will be the change in value of 'g' ?


9) Minimum work done to shift a body of mass 'm' from a circular orbit of 2R to a higher orbit of radius 3R around the earth (R = Radius of earth):


10) A satellite is moving around the earth at a height of 10 km from the surface of earth. The weight of man who weighs 60 kg on earth is:


11) The escape velocity of a body from earth is 11 km/sec. What will be its value from a planet whose radius is double but density is same as that of earth?


12) The time period of simple pendulum in a satellite is:


13) A package is released from a satellite by simply detaching it from the outer wall of the satellite. What will happen to the package?


14) A satellite is rotating close to earth. In order to make it escape the gravitational field, its velocity is to be increased by:


15) Ratio of K.E. required for the satellite to escape the earth's surface to the K.E. required to orbit just close to the earth is:


16) A satellite is in circular orbit 140 km above the planet. If the radius of planet is 5760 km then gravitational force on satellite compared with that when it is at the planet's surface is approximately is:


17) Kepler's second law regarding constancy of aerial velocity of a planet is a consequence of the law of conservation of:


18) The acceleration due to gravity on the moon is 1/6th that on the earth. If their densities are the same, the radius of moon is: (R' is the radius of earth)


19) The atmosphere is held to earth by:


20) Moon has no atmosphere because:


21) A satellite is revolving around the earth in a circular orbit 4 times the radius of the parking orbit. The time period of the satellite is:


22) If earth were a hallow sphere, what will be the intensity of gravitational field inside it?


23) A satellite revolving close to earth has a K.E., E. What energy should be given to it so as to make it escape the gravitational pull to earth?


24) If the radius of earth is reduced by 1% keeping the mass unchanged, the change in acceleration due to gravity is:


25) Infinite number of masses each of 3.0 kg are placed along x-axis at distance 1 m, 2 m, 4 m, 8 m from origin O on the axis, if G is the gravitational constant. The magnitude of gravitational field is:


26) Infinite number of masses each of 2 kg are placed along x-axis at distance 1 m, 2 m, 4 m, 8 m from the origin O, what is the magnitude of gravitational potential at 'O'? (G = gravitational constant):


27) A satellite is moving in an orbit with half the speed required to escape the earth's field. What is the height of the satellite?


28) With what speed the earth should rotate about its own axis so that a person should weigh at the equator 3/5th of his weight at present? (Take R = 6400 km)


29) A body is orbiting around the earth at a mean radius 4 times as great as the parking orbit of a satellite. The period of revolution of the body is:


30) If the satellite is stopped suddenly in its orbit and is allowed to fall freely into the earth's surface with what speed it hits the surface of earth?


31) A missile is launched with a velocity less than the escape velocity. The sum of its K.E. and P.E. is :


32) The length of the day when earth rotates fast enough to reduce the weight of the body at the equator to be zero:


33) The eccentricity of earth's elliptical orbit is 0.0167. The ratio of maximum speed to minimum speed in the orbit is:


34) The closest planet to the earth is:


35) The K.E. needed to move the body to infinite distance is:


36) A reel of massless thread unrolls itself falling down under gravity. The acceleration of its fall is:


37) The force of gravity is the least at:


38) The weight of a body at a height equal to the radius of the earth is W, its weight at a height equal to three times the radius of the earth will be:


39) You are given 32 balls identical in weight and shape except one which is heavier in weight than others. If a scale beam is provided but no weight box is available how many minimum number of weightings have to be made so as to isolate the heavier ball?


40) A star shrinks suddenly and its density increases 10 times its original value. The acceleration due to gravity increases by a factor of:


41) Three identical objects each of mass M move along circle of radius R under the action of their mutual gravitational attraction, the speed of each is:


42) Period of revolution of planet A is 8 times that of B. The distance of A from sun is how many times greater than that of B from the sun?


43) The escape velocity from earth is 11.2 km/s if the earth's mass increases to twice and radius is reduced to half of the present values. What will be escape velocity?


44) The weight of a man in a lift moving upwards is 608 N while the weight of the same man in the lift moving downwards with the same acceleration is 368 N. His normal weight in newton is:


45) The time period of a satellite of earth is 5 hours. If the separation between the earth and the satellite is increased to 4 times the previous value, the new time period will become:


46) Two spherical bodies of mass M and 5M and radii R and 2R respectively are released in free space with initial separation between their centers equal to 12R. If they attract each other due to gravitational force only then the distance covered by the smaller body just before collision is:


47) Average density of the earth:


48) A particle of mass 10 g is kept in the surface of uniform sphere of mass 100kg and radius 10 cm. Find the work done against the gravitational force between them to take the particle far away from the sphere.


49) The escape velocity on the surface of the earth is 11.2 km/s. What would be the escape velocity on the surface of another planet of the same mass but 1/4 times the radius of the earth?


50) A body weighs 72 N on the surface of earth. What is the gravitational force on it due to earth at a height equal to half the radius of the earth from the surface?


51) Knowing that mass of moon is M/81, where M is the mass of earth, find the distance of the point from the moon, where gravitational field due to earth and moon cancel each other. Given that distance between earth and moon is 60 R, where R is the radius of earth.


52) A satellite is in an orbit around the earth. If its kinetic energy is doubled, then:


53) Ratio of inertial mass to gravitational mass is:


54) The mass of the earth is 81 times that of the moon and the radius of the earth is 3.5 times that of the moon. The ratio of the escape velocity on the surface of earth to that on the surface of moon will be:


55) If mass of body is M on the earth's surface, then the mass of the same body on the moon's surface is:


56) If the radius of earth's orbit is made 1/4, the duration of an year will become:


57) The distance of geostationary satellite from centre of earth is nearest to:


58) A satellite is placed in a circular orbit around earth at such a height that it always remains stationary with respect to earth's surface. In such case, its height from the earth's surface is:


59) Escape velocity on the earth:


60) The colour of star indicates its:


61) The time period of planet X around sun is 8 times that of Y. The distance of X from the sun is how many times greater than that of Y?


62) Feeling of weightlessness in a satellite or spaceship is due to


63) If the spinning speed of the earth is increased, then the weight of the body at equator:


64) Mass of the earth has been determined through:


65) The force of gravitation is :


66) The period of revolution of a certain planet in an orbit of radius R is T. Its period of revolution is an orbit of radius 4 R will be:


67) When radius of earth is reduced by 1% without changing the mass then change in acceleration due to gravity will be:


68) The mass of a body of the moon is less than on earth. The gravitational force is less in moon than on the earth. Of the two statements:


69) The duration of day is highest at:


70) The acceleration due to gravity in the planet A is 9 times the acceleration due to gravity on planet B. A man jumps to a height of 2m on the surface of A. What is the height of jump by the same person on the planet B?


71) The velocity with which a projectile must be fired so that it escapes earth's gravitation, does not depend on:


72) A satellite orbiting around earth of radius R is shifted to an orbit of radius 2R. How many times the time taken for one revolution increase?


73) A satellite with kinetic energy E is revolving round the earth in a circular orbit. The minimum additional kinetic energy required for it to escape into outer space is:


74) The difference in length of a mean solar day and a sidereal day is about:


75) The density of newly discovered planet is twice that of earth. The acceleration due to gravity at the surface of the planet is equal to that at the surface of the earth. If the radius of the earth is R, the radius of the planet would be:


76) In an orbital motion, the angular momentum vector is:


77) The minimum kinetic energy needed to project a body form the earth's surface to infinity is:


78) For a satellite moving in an orbit around the earth, the ratio of kinetic energy to potential energy is:


79) The length of second pendulum is 1 m on earth. If mass and diameter of the planet is doubled than that of earth, then length becomes


80) What effect occurs on the frequency of a pendulum if it is taken from the earth's surface to deep into a mine?


81) Earth is revolving around the sun. If the distance of the earth from the sun is reduced to 1/4th of the present distance then the day length reduced to:


82) A simple pendulum is taken from the equator to the pole. Its period:


83) The period of a satellite in a circular orbit of radius R is T, the period of another satellite in a circular orbit of radius 4R is:


84) Force of gravity is least at:


85) The radii of circular orbits of two satellites A and B of the earth, are 4R and R, respectively. If the speed of satellite A is 3 V, then the speed of satellite B will be:


86) 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:


87) If the distance between the earth and the sun were half of its present value, the number of days in a year would have been:


88) The escape velocity from earth is 11.2 km/sec. If the mass of the earth is doubled and radius is halved. The changed escape speed is:


89) With what velocity should a particle be projected so that its height becomes equal to the radius of earth?


90) Acceleration due to gravity on a planet 'A' is 9 times that at a planet B. A man jumps to height of 2 m on the surface of A. To what height he can jump on B?


91) Two spheres of mass M and 5 M and radii R and 2 R are released in free space with initial distance between their centres being 12 R. If they move under gravitational force of attraction then the distance moved by smaller sphere just before collission is:


92) A man weighs 60 kg at the surface of earth. At what height above the surface the weight becomes 30 kg? [given R = 6400 km]


93) The variation of the acceleration due to gravity as one moves away from earth's centre is given by :