Gravitation - NCERT Based MCQs for NEET Exam

This article contains NCERT based 45 MCQ questions test on Class 11 Physics chapter "Gravitation". These questions are highly valuable for the NEET exam. You can attempt these questions in the form of an interactive quiz and calculate your score. Read the below quiz rules carefully before you start.

General Instructions

• Quiz contains 45 questions of 4 marks each.
• Correct answer (✔) will award you +4 marks and Incorrect answer (✘) will give you -1 mark.
• Total test is of 180 marks.
• Tap on box in order to select any option that you think is correct.
• Press the Submit button given in the end of quiz to calculate your score.
• There is a PDF file attached in the end of quiz. You can see detailed solutions to all questions and do self analysis from that file as well.

Question 1.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

(1) 2R

(2) 4R

(3) R/4

(4) R/2

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Question 2. Two planets of radii in the ratio 2 : 3 are made from the material of density in the ratio 3 : 2. Then the ratio of acceleration due to gravity g₁/g₂ at the surface of the two planets will be –

(1) 1

(2) 2.25

(3) 4/9

(4) 0.12

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Question 3. In a gravitational field, at a point where the gravitational potential is zero –

(1) The gravitational field is necessarily zero

(2) The gravitational field is not necessarily zero

(3) Nothing can be said definitely about the gravitational field.

(4) None of these

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Question 4. The escape velocity for the earth is v_e. The escape velocity for a planet whose radius is four times and density is nine times that of the earth, is –

(1) 36 v_e

(2) 12 v_e

(3) 6 v_e

(4) 20 v_e

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Question 5. The value of escape velocity on a certain planet is 2 km/s. Then the value of orbital speed for a satellite orbiting close to its surface is –

(1) 12 km/s

(2) 1 km/s

(3) √2 km/s

(4) 2√2 km/s

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Question 6. The condition for a uniform spherical mass m of radius r to be a black hole is [G = gravitational constant and g = acceleration due to gravity]

(1) (2Gm/r)^1/2 ≤ c

(2) (2Gm/r)^1/2 = c

(3) (2Gm/r)^1/2 ≥ c

(4) (gm/r)^1/2 ≥ c

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Question 7. Earth is revolving around the sun if the distance of the Earth from the Sun is reduced to 1/4^th of the present distance then the present day length reduced by –

(1) 1/4

(2) 1/2

(3) 1/8

(4) 1/6

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Question 8. The depth d at which the value of acceleration due to gravity becomes 1/n times the value at the surface, is [R = radius of the earth]

(1) R/n

(2) R(n-1)/n

(3) R/n²

(4) Rn/(n+1)

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Question 9. Radius of earth is around 6000 km. The weight of body at height of 6000 km from earth surface becomes –

(1) Half

(2) One-fourth

(3) One third

(4) No change

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Question 10. What should be the velocity of earth due to rotation about its own axis so that the weight at equator become 3/5 of initial value. Radius of earth on equator is 6400 km

(1) 7.4 × 10^–4 rad/sec

(2) 6.7 × 10^–4 rad/sec

(3) 7.8 × 10^–4 rad/sec

(4) 8.7 × 10^–4 rad/sec

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Question 11. If earth is supposed to be a sphere of radius R, if g₃₀ is value of acceleration due to gravity at latitude of 30° and g at the equator, the value of g – g_30° is

(1) ¼ ω²R

(2) ¾ ω²R

(3) ω²R

(4) ½ ω²R

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Question 12. A satellite with kinetic energy Ek is revolving round the earth in a circular orbit. How much more kinetic energy should be given to it so that it may just escape into outer space

(1) E_k

(2) 2E_k

(3) (1/2) E_k

(4) 3E_k

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Question 13. If a new planet is discovered rotating around Sun with the orbital radius double that of earth, then what will be its time period (in earth’s days)

(1) 1032

(2) 1023

(3) 1024

(4) 10432

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Question 14. Three particles of equal mass M are situated at the vertices of an equilateral triangle of side . What should be the velocity of each particle, so that they move on a circular path without changing -

(1) (GM/2L)^1/2

(2) (GM/L)^1/2

(3) (2GM/L)^1/2

(4) (GM/3L)^1/2

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Question 15. Two bodies of masses m and 4m are placed at a distance r. The gravitational potential at a point on the line joining them where the gravitational field is zero is

(1) zero

(2) −4 Gm/r

(3) −6 Gm/r

(4) −9 Gm/r

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Question 16. If the distance between the earth and the sun were half its present value, the number of days in a year would have been –

(1) 64.5

(2) 129

(3) 182.5

(4) 730

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Question 17. The escape velocity of a body of mass m from earth depends on –

(1) m²

(2) m¹

(3) m⁰

(4) None

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Question 18. A mass m is raised from a distance 2 R_e from surface of earth to 3R_e. Work done to do so against gravity will be-

(1) mgR_e/10

(2) mgR_e/11

(3) mgR_e/12

(4) mgR_e/14

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Question 19. If suddenly gravitational force on a satellite becomes zero it will –

(1) go in tangential direction of orbit

(2) fall on earth

(3) follow helical path towards earth

(4) follow helical path away from earth

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Question 20. The kinetic energy needed to project a body of mass m from the earth surface (radius R) to infinity is –

(1) mgR/2

(2) 2 mgR

(3) mgR

(4) mgR/4

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Question 21. 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–

(1) 22 km/s

(2) 11 km/s

(3) 11/√2 km/s

(4) 11√2 km/s

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Question 22. 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

(1) 80 hours

(2) 40 hours

(3) 20 hours

(4) 10 hours

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Question 23. Average density of the earth

(1) does not depend on g

(2) is a complex function of g

(3) is directly proportional to g

(4) is inversely proportional to g

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Question 24. 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

(1) gx

(2) gR/(R-x)

(3) gr²/(R+x)

(4) [gR²/(R+x)]^1/2

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Question 25. The time period of an earth satellite in circular orbit is independent of –

(1) The mass of the satellite.

(2) Radius of its orbit.

(3) Both the mass and radius of the orbit.

(4) Neither the mass of the satellite nor the radius of its orbit.

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Question 26. A particle of mass 10 g is kept on the surface of a uniform sphere of mass 100 kg and radius 10cm. Find the work to be done against the gravitational force between them to take the particle far away from the sphere (Take G = 6.67 × 10^–11 Nm²/kg²)

(1) 13.34 × 10^–10 J

(2) 3.33 × 10^–10 J

(3) 6.67 × 10^–9 J

(4) 6.67 × 10^–10 J

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Question 27. A satellite is moving with a constant speed v₀ in a circular orbit about the earth. An object of mass m is ejected from the satellite such that it just escapes from the gravitational pull of the earth. At the time of its ejection, the kinetic energy of the object is –

(1) 1/2 mv_o²

(2) mv_o²

(3) 3/2 mv_o²

(4) 2 mv_o²

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Question 28. In our solar system, the inter-planetary region has chunks of matter (much smaller in size compared to planets) called asteroids. They –

(1) will not move around the sun since they have very small masses compared to sun.3

(2) will move in an irregular way because of their small masses and will drift away into outer space.

(3) will move around the sun in closed orbits but not obey Kepler’s laws.

(4) will move in orbits like planets and obey Kepler’s laws.

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Question 29. 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 –

(1) will be directed towards the centre but not the same everywhere.

(2) will have the same value everywhere but not directed towards the centre.

(3) will be same everywhere in magnitude directed towards the centre.

(4) cannot be zero at any point.

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Question 30. 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 (Fig.). At subsequent times before any collision takes place:

(1) m will remain at rest.

(2) m will move towards M.

(3) m will move towards 2M.

(4) m will have oscillatory motion.

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Question 31. Satellites orbiting the earth have finite life and sometimes debris of satellites fall to the earth. This is because,

(1) the solar cells and batteries in satellites run out.

(2) the laws of gravitation predict a trajectory spiraling inwards.

(3) of viscous forces causing the speed of satellite and hence height to gradually decrease.

(4) of collisions with other satellites.

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Question 32. As observed from earth, the sun appears to move in an approximate circular orbit. For the motion of another planet like mercury as observed from earth, this would

(1) be similarly true.

(2) not be true because the force between earth and mercury is not inverse square law.

(3) not be true because the major gravitational force on mercury is due to sun.

(4) not be true because mercury is influenced by forces other than gravitational forces.

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Question 33. The change in potential energy when a body of mass m is raised to a height nRE from earth’s surface is (RE = radius of the earth)

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Question 34. 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 –

(1) g' = g/9

(2) g' = 27g

(3) g' = 9g

(4) g' = 3g

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Question 35. For a satellite moving in an orbit around the earth, the ratio of kinetic energy to potential energy is

(1) 1/2

(2) 1/√2

(3) 2

(4) √2

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Question 36. The earth is assumed to be a sphere of radius R. A platform is arranged at a height R from the surface of the earth. The escape velocity of a body from this platform is fv, where v is its escape velocity from the surface of the earth. The value of f is –

(1) 1/√2

(2) 1/3

(3) 1/2

(4) √2

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Question 37. Two satellites of earth S₁ and S₂ are moving in the same orbit. The mass of S₁ is four times the mass of S₂. Which one of the following statements is true –

(1) The potential energies of earth satellites in the two cases are equal.

(2) S₁ and S₂ are moving with the same speed

(3) The kinetic energies of the two satellites are equal.

(4) The time period of S₁ is four times that of S₂.

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Question 38. 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:

(1) t₁ = 4t₂

(2) t₁ = 2t₂

(3) t₁ = t₂

(4) t₁ > t₂

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Question 39. The height at which the acceleration due to gravity becomes g/9 (where g = the acceleration due to gravity on the surface of the earth) in terms of R, the radius of the earth, is-

(1) R/√2

(2) R/2

(3) R

(4) 2R

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Question 40. The mass of a spaceship is 1000 kg. It is to be launched from the earth's surface out into free space. The value of 'g' and 'R' (radius of earth) are 10m/s² and 6400 km respectively. The required energy for this work will be – 

(1) 6.4 × 10¹¹ Joules 

(2) 6.4 × 10⁸ Joules 

(3) 6.4 × 10⁹ Joules 

(4) 6.4 × 10¹⁰ Joules

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Question 41. Q.41 What is the minimum energy required to launch a satellite of mass m from the surface of a planet of mass M and radius R in a circular orbit at an altitude of 2R?

(1) 5GmM/6R

(2) 2GmM/3R

(3) GmM/2R

(4) GmM/3R

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Question 42. Four particles, each of mass M and equidistant from each other, move along a circle of radius R under the action of their mutual gravitational attraction. The speed of each particle is –

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Question 43. From a solid sphere of mass M and radius R, a spherical portion of radius (R/2) is removed, as shown in the figure. Taking gravitational potential V = 0 at r = , the potential at the centre of the cavity thus formed is (G = gravitational constant)

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Question 44. A satellite is revolving in a circular orbit at a height ‘h’ from the earth’s surface (radius or earth R; h << R ). The minimum increase in its orbital velocity required, so that the satellite could escape from the earth’s gravitational field, is close to: (Neglect the effect of atmosphere)

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Question 45. The variation of acceleration due to gravity g with distance d from centre of the earth is best represented by (R = Earth’s radius) :

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Detailed Solutions

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