# MCQs For NCERT Class 11 Physics Chapter 8 Gravitation

Please refer to the MCQ Questions for Class 11 Physics Chapter 8 Gravitation with Answers. The following Gravitation Class 11 Physics MCQ Questions have been designed based on the latest syllabus and examination pattern for Class 11. Our experts have designed MCQ Questions for Class 11 Physics with Answers for all chapters in your NCERT Class 11 Physics book.

## Gravitation Class 11 MCQ Questions with Answers

See below Gravitation Class 11 Physics MCQ Questions, solve the questions and compare your answers with the solutions provided below.

Question. 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
(a) 10 hours
(b) 80 hours
(c) 40 hours
(d) 20 hours

C

Question. Satellites orbitting the earth have finite life and sometimes debris of satellites fall to the earth. This is because
(a) the solar cells and batteries in satellites run out
(b) the laws of gravitation predict a trajectory spiralling inwards
(c) of viscous forces causing the speed of satellite and hence height to gradually decrease
(d) of collisions with other satellites

C

Question. Both the earth and the moon are subject to the gravitational force of the sun. As observed from the sun, the orbit of the moon
(a) will be elliptical
(b) will not be strictly elliptical because the total gravitational force on it is not central
(c) is not elliptical but will necessarily be a closed curve
(d) deviates considerably from being elliptical due to influence of planets other than the earth

B

Question. At sea level, a body will have minimum weight at
(a) pole
(b) equator
(c) 42° south latitude
(d) 37° north latitude

B

Question. In our solar system, the inter-planetary region has chunks of matter (much smaller in size compared to planets) called asteroids. They
(a) will not move around the sun, since they have very small masses compared to the sun
(b) will move in an irregular way because of their small masses and will drift away into outer space
(c) will move around the sun in closed orbits but not obey Kepler’s laws
(d) will move in orbits like planets and obey Kepler’s laws

D

Question. Choose the wrong option.
(a) Inertial mass is a measure of difficulty of accelerating a body by an external force whereas the gravitational mass is relevant in determining the gravitational force on it by an external mass
(b) That the gravitational mass and inertial mass are equal is an experimental result
(c) That the acceleration due to gravity on the earth is the same for all bodies is due to the equality of gravitational mass and inertial mass
(d) Gravitational mass of a particle like proton can depend on the presence of neighbouring heavy objects but the inertial mass cannot

D

Question. A black hole is an object whose gravitational field is so strong that even light cannot escape from it. To what approximate radius would earth (mass = 5.98 × 1024 kg) have to be compressed to be a black hole?
(a) 10– 9 m
(b) 10– 6 m
(c) 10– 2 m
(d) 100 m

C

Question. A satellite S is moving in an elliptical orbit around the earth.
The mass of the satellite is very small compared to the mass of the earth. Then,
(a) the total mechanical energy of S varies periodically with time.
(b) the linear momentum of S remains constant in magnitude.
(c) the acceleration of S is always directed towards the centre of the earth.
(d) the angular momentum of S about the centre of the earth changes in direction, but its magnitude remains constant.

C

Question. A planet moving along an elliptical orbit is closest to the sun at a distance r1 and farthest away at a distance of r2. If v1 and v2 are the linear velocities at these points respectively, then the ratio v
v1/V2 is
(a) (r1/r2)2
(b) r2/r1
(c) (r2/r1)2
(d) r1/r2

B

Question. The period of revolution of planet A around the sun is 8 times that of B. The distance of A from the sun is how many times greater than that of B from the sun?
(a) 4
(b) 5
(c) 2
(d) 3

A

Question. The distance of two planets from the sun are 1013 m and 1012 m respectively. The ratio of time periods of the planets is
(a) 10
(b) 10 10
(c) 10
(d) 1/ 10

B

Question. A planet is moving in an elliptical orbit around the sun. If T, V, E and L stand respectively for its kinetic energy, gravitational potential energy, total energy and magnitude of angular momentum about the centre of force, which of the following is correct ?
(a) T is conserved.
(b) V is always positive.
(c) E is always negative.
(d) L is conserved but direction of vector L changes continuously.

C

Question. Two astronauts are floating in gravitational free space after having lost contact with their spaceship.
The two will
(a) move towards each other
(b) move away from each other
(c) will become stationary
(d) keep floating at the same distance between them.

A

Question. Kepler’s third law states that square of period of revolution (T) of a planet around the sun, is proportional to third power of average distance r between sun and planet i.e. T2 = Kr3 here K is constant. If the masses of sun and planet are M and m respectively then as per Newton’s law of gravitation force of attraction between them is F = GMm /r2 , here
G is gravitational constant. The relation between G and K is described as
(a) K = G
(b) K =1/G
(c) GK = 4p2
(d) GMK = 4p2

D

Question. Two spheres of masses m and M are situated in air and the gravitational force between them is F. The space around the masses is now filled with a liquid of specific gravity 3. The gravitational force will now be
(a) 3 F
(b) F
(c) F/3
(d) F/9

B

Question. The value of acceleration due to gravity, at earth surface is g. Its value at the centre of the earth, which we assume as a sphere of radius R and of uniform mass density, will be :
(a) 10 R m/s2
(b) zero
(c) 5 R m/s
(d) 20 R m/s2

B

Question. Gravitational mass is proportional to the gravitational :
(a) intensity
(b) field
(c) force
(d) none of these

C

Question. Escape velocity of a body when projected from the earth’s surface is 11.2 km/sec. If it is projected at an angle of 50° from the horizontal, then escape velocity is:
(a) 12.8 km/sec
(b) 16.2 km/sec
(c) 11.2 km/sec
(d) 11.8 km/sec

C

Question. Knowing that the mass of the moon is 1/81 times that of earth and its radius is 1/4 the radius of earth. If the escape velocity at the surface of the earth is 11.2 km/sec, then the value of escape velocity at the surface of the moon is
(a) 2.5 km/sec
(b) 0.14 km/sec
(c) 5 km/sec
(d) 8 km/sec

A

Question. Potential energy of a satellite having mass m and rotating at a height of 6.4 × 106 m from the earth centre is
(a) – 0.2 mg Re
(b) – 2 mg Re
(c) –0.5 mg Re
(d) – mg Re

D

Question. The escape velocity from the earth is 11.2 km/sec. The escape velocity from a planet having twice the radius and the same mean density as the earth, is :
(a) 11.2 km/sec
(b) 22.4 km/sec
(c) 15.00 km/sec
(d) 5.8 km/sec

B

Question. Hubble’s law is related with
(a) planetary motion
(b) speed of galaxy
(c) black hole
(d) comet

B

Question. The radius of earth is about 6400 km and that of mass is about 3200 km. The mass of the earth is about 10 times of the mass. The object weighs 200 N on earth surface, then its weight on the surface of mars will be
(a) 80 N
(b) 40 N
(c) 20 N
(d) 8 N

A

Question. A satellite is launched into a circular orbit of radius R around the earth. While a second satellite launched into an orbit of radius 1.01R.
The period of the second satellite is longer than the first one by approximately :
(a) 3.0%
(b) 1.5%
(c) 0.7%
(d) 1.0%

B

Question. The velocity with which a projectile must be fired so that it escapes earth’s gravitation does not depend on :
(a) mass of the earth
(b) mass of the projectile
(c) radius of the projectile’s orbit
(d) gravitational constant

B

Question. Gravitational force is required for
(a) stirring of liquid
(b) convection
(c) conduction

B

Question. A body of weight 72 N moves from the surface of earth at a height half of the radius of earth, then gravitational force exerted on it will be
(a) 36 N
(b) 32 N
(c) 144 N
(d) 50 N

B

Question. The earth (mass = 6 × 1024 kg) revolves around the sun with an angular velocity of 2 × 10–7 rad/s in a circular orbit of radius 1.5 × 108 km. The force exerted by the sun on the earth, in newton, is
(a) 36 × 1021
(b) 27 × 1039
(c) zero
(d) 18 × 1025

A

Question. If the gravitational force between two objects were proportional to 1/R (and not as 1/R2), where R is the distance between them, then a particle in a circular path (under such a force) would have its orbital speed v, proportional to
(a) R
(b) R0 (independent of R)
(c) 1/R2
(d) 1/R

B

Question. If the mass of the Sun were ten times smaller and the universal gravitational constant were ten times larger in magnitude, which of the following is not correct?
(a) Raindrops will fall faster.
(b) Walking on the ground would become more difficult.
(c) Time period of a simple pendulum on the Earth would decrease.
(d) g on the Earth will not change.

D

Question. Imagine a new planet having the same density as that of earth but it is 3 times bigger than the earth in size. If the acceleration due to gravity on the surface of earth is g and that on the surface of the new planet is g′, then
(a) g′ = g/9
(b) g′ = 27g
(c) g′ = 9g
(d) g′ = 3g

D

Question. The density of a 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
(a) 2R
(b) 4R
(c) 1/4 R
(d) 1/2 R

D

Question. The acceleration due to gravity on the planet A is 9 times the acceleration due to gravity on planet B.
A man jumps to a height of 2 m on the surface of A.
What is the height of jump by the same person on the planet B ?
(a) (2/9) m
(b) 18 m
(c) 6 m
(d) (2/3) m

B

Question. The radius of earth is about 6400 km and that of mars is 3200 km. The mass of the earth is about 10  times mass of mars. An object weighs 200 N on the surface of earth. Its weight on the surface of mars will be
(a) 20 N
(b) 8 N
(c) 80 N
(d) 40 N

C

Question. A body weighs 72 N on the surface of the earth.
What is the gravitational force on it, at a height equal to half the radius of the earth?
(a) 48 N
(b) 32 N
(c) 30 N
(d) 24 N

B

Question. A body weighs 200 N on the surface of the earth. How much will it weigh half way down to the centre of the earth ?
(a) 100 N
(b) 150 N
(c) 200 N
(d) 250 N

A

Question. The acceleration due to gravity at a height 1 km above the earth is the same as at a depth d below the surface of earth. Then
(a) d = 1 km
(b) d = 3/2km
(c) d = 2 km
(d) d = 1/2km

C

Question. The height at which the weight of a body becomes (1/16 ) th, its weight on the surface of earth (radius R), is
(a) 5R
(b) 15R
(c) 3R
(d) 4R

3R

Question. The work done to raise a mass m from the surface of the earth to a height h, which is equal to the radius of the earth, is
(a) 3/2 mgR
(b) mgR
(c) 2mgR
(d) 1/2mgR