# MCQ Questions Chapter 8 Gravitation Class 11 Physics

Please refer to MCQ Questions Chapter 8 Gravitation Class 11 Physics with answers provided below. These multiple-choice questions have been developed based on the latest NCERT book for class 11 Physics issued for the current academic year. We have provided MCQ Questions for Class 11 Physics for all chapters on our website. Students should learn the objective based questions for Chapter 8 Gravitation in Class 11 Physics provided below to get more marks in exams.

## Chapter 8 Gravitation MCQ Questions

Please refer to the following Chapter 8 Gravitation MCQ Questions Class 11 Physics with solutions for all important topics in the chapter.

MCQ Questions Answers for Chapter 8 Gravitation Class 11 Physics

Question. There is no atmosphere on the moon because
(a) it is closer to the earth and also it has the inactive inert gases in it.
(b) it is too for from the sun and has very low pressure in its outer surface.
(c) escape velocity of gas molecules is greater than their root mean square velocity.
(d) escape velocity of gas molecules is less than their root mean square velocity.

D

Question. A man waves his arms while walking. This is to
(a) keep constant velocity
(b) ease the tension
(c) increase the velocity
(d) balance the effect of earth’s gravity

D

Question. A body starts from rest from a point distance R0 from the centre of the earth. The velocity acquired by the body when it reaches the surface of the earth will be (R represents radius of the earth).

B

Question. A missile is launched with a velocity less than escape velocity. The sum of its kinetic and potential energies is
(a) zero
(b) negative
(c) positive
(d) may be positive, negative or zero.

B

Question. The maximum kinetic energy of a planet moving around the sun is at a position
(a) A
(b) B
(c) C
(d) D

A

Question. Which of the following graphs represents the motion of a planet moving about the sun ?

C

Question. Two planets of radii r1 and r2 are made from the same material. The ratio of the acceleration due to gravity g1/g2 at the surfaces of the two planets is
(a) r1/r2
(b) r2/r1
(c) (r1/r2)2
(d) (r2/r1)2

A

Question. A planet moves around the sun. At a point P it is closest from the sun at a distance d1 and has a speed v1. At another point Q, when it is farthest from the sun at a distnace d2 its speed will be
(a) d21 v1 / d22
(b) d2 v1 / d1
(c) d1 v1 / d2
(d) d22 v1 / d21

C

Question. What would be the length of a sec. pendulum at a planet (where acc. due to gravity is g/4) if it’s length on earth is l

C

Question. Due to rotation of the earth the acceleration due to gravity g is
(a) maximum at the equator and minimum at the poles
(b) minimum at the equator and maximum at the poles
(c) same at both places
(d) None of these

B

Question. Time period of a simple pendulum inside a satellite orbiting earth is
(a) zero
(b) ∞
(c) T
(d) 2 T

B

Question. A satellite is orbiting around the earth near its surface. If its kinetic energy is doubled, then
(a) it will remain in the same orbit.
(b) it will fall on the earth.
(c) it will revolve with greater speed.
(d) it will escape out of the gravitational field of the earth.

D

Question. The ratio of the radii of the planets R1 and R2 is k. The ratio of the acceleration due to gravity is r. The ratio of the escape velocities from them will be
(a) k r
(b) √kr
(c) √(k / r)
(d) √(r / k)

B

Question. The kinetic energy needed to project a body of mass m from the earth surface (radius R) to infinity is
(a) mgR/2
(b) 2mgR
(c) mgR
(d) mgR/4

C

Question. The escape velocity of a body depends upon mass as
(a) m0
(b) m1
(c) m2
(d) m3.

A

Question. The escape velocity from the earth’s surface is 11 km/s. The escape velocity from a planet having twice the radius and same mean density as that of earth is
(a) 5.5 km/s
(b) 11 km/s
(c) 22 km/s
(d) None of these

C

Question. The radius of a planet is 1/4th of Re and its acc. due to gravity is 2g. What would be the value of escape velocity on the planet, if escape velocity on earth is ve.

A

Question. Two satellites revolve round the earth with orbital radii 4R and 16R, if the time period of first satellite is T then that of the other is
(a) 4 T
(b) 42/3 T
(c) 8 T
(d) None of these

C

Question. If ve and v0 represent the escape velocity and orbital velocity of a satellite corresponding to a circular orbit of radius R, then
(a) ve = vo
(b) ve = √2 vo
(c) ve = (1/√2) vo
(d) ve and vo are not related

B

Question. A planet revolves in an elliptical orbit around the sun. The semi-major and semi-minor axes are a and b. Then the square of time period, T is directly proportional to

A

Question. The weight of an object in the coal mine, sea level and at the top of the mountain, are respectively W1, W2 and W3 then
(a) W1< W2 > W3
(b) W1= W2 = W3
(c) W1< W2 < W3
(d) W1> W2 > W3

A

Question. Which of the following quantities do not depend upon the orbital radius of the satellite ?

D

Question. If the gravitational force had varied as r–5/2 instead of r–2; the potential energy of a particle at a distance ‘r’ from the centre of the earth would be proportional to
(a) r-1
(b) r-2
(c) r-3 / 2
(d) r-5 / 2

C

Question. The orbital velocity of an artificial satellite in a circular orbit very close to Earth is v. The velocity of a geosynchronous satellite orbiting in a circular orbit at an altitude of 6R from Earth’s surface will be

A

Question. The potential energy of a satellite of mass m and revolving at a height Re above the surface of earth where Re = radius of earth, is
(a) – m g Re
(b) – mgRe/2
(c) – mgRe/3
(d) – mgRe/4

B

Question. Two point masses each equal to 1 kg attract one another with a force of 10–10 N. The distance between the two point masses is (G = 6.6 × 10–11 MKS units)
(a) 8 cm
(b) 0.8 cm
(c) 80 cm
(d) 0.08 cm

C

Question. Escape velocity when a body of mass m is thrown vertically from the surface of the earth is v, what will be the escape velocity of another body of mass 4 m is thrown vertically
(a) v
(b) 2v
(c) 4v
(d) None of these

A

Question. There are two bodies of masses 103 kg and 105 kg separated by a distance of 1 km. At what distance from the smaller body, the intensity of gravitational field will be zero
(a) 1/9 km
(b) 1/10 km
(c) 1/11 km
(d) 10/11 km

C

Question. The distance of neptune and saturn from the sun is nearly 1013 and 1012 meter respectively. Assuming that they move in circular orbits, their periodic times will be in the ratio
(a) 10
(b) 100
(c) 10√10
(d) 1000

C

Question. Taking the gravitational potential at a point infinte distance away as zero, the gravitational potential at a point A is –5 unit. If the gravitational potential at point infinite distance away is taken as + 10 units, the potential at point A is
(a) – 5 unit
(b) + 5 unit
(c) + 10 unit
(d) + 15 unit

B

Question. The mass of the moon is 1/81 of earth’s mass and its radius 1/4 that of the earth. If the escape velocity from the earth’s surface is 11.2 km/sec, its value from the surface of the moon will be
(a) 0.14 kms–1
(b) 0.5 kms–1
(c) 2.5 kms–1
(d) 5.0 kms–1

C

Question. A planet of mass 3 × 1029 gm moves around a star with a constant speed of 2 × 106 ms–1 in a circle of radii 1.5 × 1014 cm. The gravitational force exerted on the planet by the star is
(a) 6.67 × 1022 dyne
(d) 8 × 1027 Newton
(c) 8 × 1026 N
(d) 6.67 × 1019 dyne

C

Question. Two bodies of masses 10 kg and 100 kg are separated by a distance of 2m ( G = 6.67 × 10–11 Nm2 kg–2). The gravitational potential at the mid point on the line joining the two is
(a) 7.3 × 10–7 J/kg
(b) 7.3 × 10–9 J/kg
(c) –7.3 × 10–9 J/kg
(d) 7.3 × 10–6 J/kg

C

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. A geostationary satellite is orbiting the earth at a height of 5R above that surface of the earth, R being the radius of the earth. The time period of another satellite in hours at a height of 2R from the surface of the earth is
(a) 5
(b) 10
(c) 6√2
(d) 6/√2

C

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. The escape velocity for a body projected vertically upwards from the surface of earth is 11 km/s. If the body is projected at an angle of 45º with the vertical, the escape velocity will be
(a) 22 km/s
(b) 11 km/s
(c) (11√2)km/s
(d) 11 2 km/s

B

Question. If the length of a simple pendulum is increased by 2%, then the time period
(a) increases by 2%
(b) decreases by 2%
(c) increases by 1%
(d) decreases by 1%

C

Question. The time period of a satellite in a circular orbit of radius R is T, the period of another satellite in a circular orbit of radius 4 R is
(a) 4 T
(b) T/4
(c) 8 T
(d) T/8

C

Question. The kinetic energy of a satellite in its orbit around the earth is E. What should be the kinetic energy of the satellite so as to enable it to escape from the gravitational pull of the earth?
(a) 4 E
(b) 2 E
(c) 2 E
(d) E

B

Question. A satellite of mass m revolves around the earth of radius R at a height ‘x’ from its surface. If g is the acceleration due to gravity on the surface of the earth, the orbital speed of the satellite is

D

Question. The time period of an earth satellite in circular orbit is independent of
(a) both the mass and radius of the orbit
(c) the mass of the satellite
(d) neither the mass of the satellite nor the radius of its orbit.

C

Question. If the change in the value of g at the height h above the surface of the earth is the same as at a depth ‘x’ below it, then (both x and h being much smaller than the radius of the earth)
(a) x = h
(b) x = 2 h
(c) x = h/2
(d) x = h2

B

Question. An earth satellite of mass m revolves in a circular orbit at a height h from the surface of the earth. R is the radius of the earth and g is acceleration due to gravity at the surface of the earth. The velocity of the satellite in the orbit is given by
(a) gR2/(R + h)
(b) gR
(c) gR/(R – h)
(d) √[gR2 / (R + h)]

D

Question. The radius of the earth is 4 times that of the moon and its mass is 80 times that of the moon. If the acceleration due to gravity on the surface of the earth is 10 m/s2, then on the surface of the moon its value will be
(a) 1 ms–2
(b) 2 ms–2
(c) 3 ms–2
(d) 4 ms–2

B

Question. Mass of the Earth has been determined through
(a) use of Kepler’s T2/R3 constancy law and Moon’s period
(b) sampling the density of Earth’s crust and using Earth’s radius
(c) Cavendish’s determination of G and using Earth radius and g at its surface
(d) use of periods of satellites at different heights above Earth’s surface and known radius of Earth

C

Question. There are _______ gravitational lines of force inside a spherically symmetric shell.
(a) infinitely many
(b) zero
(c) varying number depending upon surface area
(d) varying number depending upon volume

B

Question. Energy required to move a body of mass m from an orbit of radius 2R to 3R is
(a) GMm/12R2
(b) GMm/3R2
(c) GMm/8R
(d) GMm/6R

D

Question. Consider Earth to be a homogeneous sphere. Scientist A goes deep down in a mine and scientist B goes high up in a balloon. The gravitational field measured by
(a) A goes on decreasing and that by B goes on increasing
(b) B goes on decreasing and that by A goes on increasing
(c) each decreases at the same rate
(d) each decreases at different rates

D

Question. If the mass of earth is eighty times the mass of a planet and diameter of the planet is one fourth that of earth, then acceleration due to gravity on the planet would be
(a) 7.8 m/s2
(b) 9.8 m/s2
(c) 6.8 m/s2
(d) 2.0 m/s2

D

Question. A uniform ring of mass m and radius r is placed directly above a uniform sphere of mass M and of equal radius. The centre of the ring is directly above the centre of the sphere at a distance r 3 as shown in the figure. The gravitational force exerted by the sphere on the ring will be

C

Question. The gravitational potential difference between the surface of a planet and a point 20 m above the surface is 2 joule/kg. If the gravitational field is uniform, then the work done in carrying a 5 kg body to a height of 4 m above the surface is
(a) 2 J
(b) 20 J
(c) 40 J
(d) 10 J

A

Question. The radii of two planets are respectively R1 and R2 and their densities are respectively r1 and r2. The ratio of the accelerations due to gravity at their surfaces is

D

Question. If value of acceleration due to gravity changes from one place to another, which of the following forces will undergo a change ?
(a) Viscous force
(b) Buoyant force
(c) Magnetic force
(d) All of the above

B

Question. The ratio of the kinetic energy required to be given to a satellite so that it escapes the gravitational field of Earth to the kinetic energy required to put the satellite in a circular orbit just above the free surface of Earth is
(a) 1
(b) 2
(c) 3
(d) 9

B

Question. The amount of work done in lifting a mass ‘m’ from the surface of the earth to a height 2R is
(a) 2mgR
(b) 3mgR
(c) (3/2)mgR
(d) (2/3)mgR

D

Question. An artificial satellite moving in a circular orbit around the earth has a total (K.E. + P.E.) is E0. Its potential energy is –
(a) –E0
(b) 1.5 E0
(c) 2E0
(d) E0

C

Question. A solid sphere of uniform density and radius R applies a gravitational force of attraction equal to F1 on a particle placed at A, distance 2R from the centre of the sphere.

A spherical cavity of radius R/2 is now made in the sphere as shown in the figure. The sphere with cavity now applies a gravitational force F2 on the same particle placed at A. The ratio F2/F1 will be
(a) 1/2
(b) 3
(c) 7
(d) 1/9

D

Question. A satellite of mass ‘m’, moving around the earth in a circular orbit of radius R, has angular momentum L. The areal velocity of satellite is (Me = mass of earth)
(a) L /2m
(b) L /m
(c) 2L /m
(d) 2L /Me