# MCQ Chapter Chapter 8 Gravitation Class 11 Physics

Please refer to Gravitation MCQ Questions Class 11 Physics below. These MCQ questions for Class 11 Physics with answers have been designed as per the latest NCERT, CBSE books, and syllabus issued for the current academic year. These objective questions for Gravitation will help you to prepare for the exams and get more marks.

## Gravitation MCQ Questions Class 11 Physics

Please see solved MCQ Questions for Gravitation in Class 11 Physics. All questions and answers have been prepared by expert faculty of standard 11 based on the latest examination guidelines.

### MCQ Questions Class 11 Physics Gravitation

Question. A planet is revolving around the sun in an elliptical orbit. Its closests distance from the sun is rmin. The farthest distance from the sun is rmax. If the orbital angular velocity of the planet when it is nearest to the sun is w, then the orbital angular velocity at the point when it is at the farthest distance from the sun is

D

Question. If there were a small gravitational effect, then which of the following forces will undergo a change?
(a) Viscous force
(b) Electrostatic force
(c) Magnetic force
(d) Archimedes’ uplift

B

Question. wo spherical bodies of mass M and 5M and radii R and 2R respectively are released in free space with initial separation between their centres equal to 12 R. If they attract each other due to gravitational force only, then the distance covered by the smaller body just before collision is
(a) 2.5 R
(b) 4.5 R
(c) 7.5 R
(d) 1.5 R

C

Question. The largest and the shortest distance of the earth from the sun are r1 and r2. Its distance from the sun when it is at perpendicular to the major-axis of the orbit drawn from the sun
(a) (r1 + r2 ) / 4
(b) (r1 + r2 ) /(r1 – r2 )
(c) 2 r1 r2 /(r1 + r2)
(d) (r1 + r2 ) / 3

C

Question. If the radius of the earth were to shrink by one per cent, its mass remaining the same, the acceleration due to gravity on the earth’s surface would
(a) decrease
(b) remain unchanged
(c) increase
(d) None of these

C

Question. A ball is dropped from a satellite revolving around the earth at height of 120 km. The ball will
(a) continue to move with same speed along a straight
line tangentially to the satellite at that time
(b) continue to move with same speed along the original orbit of satellite.
(c) fall down to earth gradually
(d) go far away in space

B

Question. The orbital velocity of an artificial satellite in a circular orbit just above the centre’s surface is u. For a satellite orbiting at an altitude of half of the earth’s radius, the orbital velocity is

A

Question. Two identical geostationary satellites are moving with equal speeds in the same orbit but their sense of rotation brings them on a collision course. The debris will
(a) fall down
(b) move up
(c) begin to move from east to west in the same orbit
(d) begin to move from west to east in the same orbit

A

Question. If earth is supposed to be a sphere of radius R, if g30 is value of acceleration due to gravity at lattitude of 30° and g at the equator, the value of g – g30 is

B

Question. The gravitational force of attraction between a uniform sphere of mass M and a uniform rod of length l and mass m oriented as shown is

(c) Mmr2 + l
(d) (r2 + l)mM

A

Question. In a region of only gravitational field of mass ‘M’ a particle is shifted from A to B via three different paths in the figure. The work done in different paths are W1, W2, W3 respectively then

(a) W1 = W2 = W3
(b) W1 > W2 > W3
(c) W1 = W2 > W3
(d) W1 < W2 < W3

A

Question. Suppose, the acceleration due to gravity at the Earth’s surface is 10 m s–2 and at the surface of Mars it is 4.0 m s–2. A 60 kg pasenger goes from the Earth to the Mars in a spaceship moving with a constant velocity. Neglect all other objects in the sky. Which part of figure best represents the weight (net gravitational force) of the passenger as a function of time?

(a) A
(b) B
(c) C
(d) D

C

Question. A projectile is fired vertically from the Earth with a velocity kve where ve is the escape velocity and k is a constant less than unity. The maximum height to which projectile rises, as measured from the centre of Earth, is

C

Question. Explorer 38, a radio-astronomy satellite of mass 200 kg, circles the Earth in an orbit of average radius 3R/2 where R is the radius of the Earth. Assuming the gravitational pull on a mass of 1 kg at the earth’s surface to be 10 N, calculate the pull on the satellite
(a) 889 N
(b) 89 N
(c) 8889 N
(d) 8.9 N

A

Question. A diametrical tunnel is dug across the Earth. A ball is dropped into the tunnel from one side. The velocity of the ball when it reaches the centre of the Earth is …. (Given : gravitational potential at the centre of Earth = – 3GM/2R)

B

Question. Four similar particles of mass m are orbiting in a circle of radius r in the same angular direction because of their mutual gravitational attractive force. Velocity of a particle is given by

A

Question. A man of mass m starts falling towards a planet of mass M and radius R. As he reaches near to the surface, he realizes that he will pass through a small hole in the planet. As he enters the hole, he sees that the planet is really made of two pieces a spherical shell of negligible thickness of mass 2M/ 3 and a point mass M/3 at the centre. Change in the force of gravity experienced by the man is

A

Question. The percentage change in the acceleration of the earth towards the sun from a total eclipse of the sun to the point where the moon is on a side of earth directly opposite to the sun is

C

Question. A cavity of radius R/2 is made inside a solid sphere of radius R. The centre of the cavity is located at a distance R/ 2 from the centre of the sphere. The gravitational force on a particle of mass ‘m’ at a distance R/2 from the centre of the sphere on the line joining both the centres of sphere and cavity is – (opposite to the centre of gravity) [Here g = GM/R², where M is the mass of the sphere]
(a) mg/2
(b) 3mg/8
(c) mg/16
(d) None of these

B

Question. A (nonrotating) star collapses onto itself from an initial radius Ri with its mass remaining unchanged. Which curve in figure best gives the gravitational acceleration ag on the surface of the star as a function of the radius of the star during the collapse

(a) a
(b) b
(c) c
(d) d

B

Question. A satellite is launched into a circular orbit of radius R around the earth. A second satellite is launched into an orbit of radius 1.01 R. The period of second satellite is larger than the first one by approximately
(a) 0.5%
(b) 1.0%
(c) 1.5%
(d) 3.0%

C

Question. The earth is assumed to be sphere of radius R. A platform is arranged at a height R from the surface of Earth. The escape velocity of a body from this platform is kv, where v is its escape velocity from the surface of the earth. The value of k is
(a) 1/√2
(b) 1/3
(c) 1/2
(d) √2

A

Question. A planet of mass m moves around the sun of mass M in an elliptical orbit. The maximum and minimum distance of the planet from the sun are r1 and r2 respectively. The time period of planet is proportional to

B

Question. The change in potential energy, when a body of mass m is raised to a height nR from the earth’s surface is (R = radius of earth)

D

Question. The escape velocity from a planet is ve. A tunnel is dug along a diameter of the planet and a small body is dropped into it at the surface. When the body reaches the centre of the planet, its speed will be
(a) ve
(b) ev/√2
(c) ve/2
(d) zero

B

Question. If gE and gM are the accelerations due to gravity on the surfaces of the earth and the moon respectively and if Millikan’s oil drop experiment could be performed on the two surfaces, one will find the ratio
electronic charge on the moon/electronic charge on the earth, to be
(a) gM / gE
(b) 1
(c) 0
(d) gE / gM

B

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 = (3/2) km
(c) d = 2 km
(d) d = (1/2) km

C

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) ½ R
(b) 2 R
(c) 4 R
(d) 1/4 R

A

Question. For a satellite moving in an orbit around the earth, the ratio of kinetic energy to potential energy is
(a) 1/2
(b) 1/√2
(c) 2
(d) √2

A

Question. The figure shows elliptical orbit of a planet m about the sun S. The shaded area SCD is twice the shaded area SAB. If t1 is the time for the planet to move from C to D and t2 is the time to move from A to B then :

(a) t1 = 4t2
(b) t1 = 2t2
(c) t1 = t2
(d) t1 > t2

B

Question. 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
(a) 3 V/4
(b) 6 V
(c) 12 V
(d) 3 V/2

B

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 v1/v2 is
(a) (r1/r2)2
(b) r2/r1
(c) (r2/r1)2
(d) r1/r2

B

Question. A particle of mass m is thrown upwards from the surface of the earth, with a velocity u. The mass and the radius of the earth are, respectively, M and R. G is gravitational constant and g is acceleration due to gravity on the surface of the earth. The minimum value of u so that the particle does not return back to earth, is

A

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. Which one of the following graphs represents correctly the variation of the gravitational field intensity (I) with the distance (r) from the centre of a spherical shell of mass M and radius a ?

D

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. The earth is an approximate sphere. If the interior contained matter which is not of the same density everywhere, then on the surface of the earth, the acceleration due to gravity
(a) will be directed towards the centre but not the same everywhere
(b) will have the same value everywhere but not directed towards the centre
(c) will be same everywhere in magnitude directed towards the centre
(d) cannot be zero at any point

D

Question. As observed from the earth, the sun appears to move in an approximate circular orbit. For the motion of another planet like mercury as observed from the earth, this would
(a) be similarly true
(b) not be true because the force between the earth and mercury is not inverse square law
(c) not be true because the major gravitational force on mercury is due to the sun
(d) not be true because mercury is influenced by forces other than gravitational force

C

Question. A particle of mass M is situated at the centre of a spherical shell of same mass and radius a. The gravitational potential at a point situated at α/2 distance from the centre, will be
(a) -(3GM/a)
(b) -(2GM/a)
(c) -(GM/a)
(d) -(4GM/a)

A

Question. Different points in the earth are at slightly different distances from the sun and hence experience different forces due to gravitation. For a rigid body, we know that if various forces act at various points in it, the resultant motion is as if a net force acts on the CM (centre of mass) causing translation and a net torque at the CM causing rotation around an axis through the CM. For the earth-sun system (approximating the earth as a uniform density sphere).
(a) the torque is zero
(b) the torque causes the earth to spin
(c) the rigid body result is not applicable since the earth is not even approximately a rigid body
(d) the torque causes the earth to move around the sun

A

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. 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) GMK = 4π2
(b) K = G
(c) K = 1/G
(d) GK = 4π2

A

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. A spherical uniform planet is rotating about its axis. The velocity of a point on its equator is V. Due to the rotation of planet about its axis the acceleration due to gravity g at equator is 1/2 of g at poles. The escape velocity of a particle on the pole of planet in terms of V is
(a) Ve = 2V
(b) Ve = V
(c) Ve = V/2
(d) Ve = √3V

A

Question. Particles of masses 2M, m and M are respectively at points A, B and C with AB = 1/2 (BC). m is much-much smaller than M and at time t = 0, they are all at rest as given in figure. At subsequent times before any collision takes place.

(a) m will remain at rest
(b) m will move towards M
(c) m will move towards 2M
(d) m will have oscillatory motion

C

Question. Infinite number of bodies, each of mass 2 kg are situated on x-axis at distances 1m, 2m, 4m, 8m, ….. respectively, from the origin. The resulting gravitational potential due to this system at the origin will be

C

Question. The radius of a planet is twice the radius of earth. Both have almost equal average mass-densities. If VP and VE are escape velocities of the planet and the earth, respectively, then
(a) VE = 1.5VP
(b) VP = 1.5VE
(c) VP = 2VE
(d) VE = 3VP

C

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 particle of mass ‘m’ is kept at rest at a height 3R from the surface of earth, where ‘R’ is radius of earth and ‘M’ is mass of earth. The minimum speed with which it should be projected, so that it does not return back, is (g is acceleration due to gravity on the surface of earth)

B

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

A

Question. Two spherical bodies of mass M and 5 M and radii R and 2 R released in free space with initial separation between their centres equal to 12 R. If they attract each other due to gravitational force only, then the distance covered by the smaller body before collision is
(a) 4.5 R
(b) 7.5 R
(c) 1.5 R
(d) 2.5 R

B

Question. A remote – sensing satellite of earth revolves in a circular orbit at a height of 0.25 × 106 m above the surface of earth. If earth’s radius is 6.38 × 106 m and g = 9.8 ms–2, then the orbital speed of the satellite is:
(a) 8.56 km s–1
(b) 9.13 km s–1
(c) 6.67 km s–1
(d) 7.76 km s–1

D

Question. Dependence of intensity of gravitational field (E) of earth with distance (r) from centre of earth is correctly represented by:

B

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 body of mass ‘m’ is taken from the earth’s surface to the height equal to twice the radius (R) of the earth. The change in potential energy of body will be

A

Question. The ratio of escape velocity at earth (ve) to the escape velocity at a planet (vp) whose radius and mean density are twice as that of earth is :
(a) 1 : 2
(b) 1 : 2 √2
(c) 1 : 4
(d) 1 : 2

B

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. At what height from the surface of earth the gravitational potential and the value of g are –5.4 × 107 J kg–1 and 6.0 ms–2 respectively ?
Take the radius of earth as 6400 km :
(a) 2600 km
(b) 1600 km
(c) 1400 km
(d) 2000 km