Gravitation is one of the most important topics in JEE Main and is considered to be highly scoring. Gravitation is considered to be a natural phenomenon and is the attractional force between two objects with energy. The force of gravitational attraction was first observed by Isaac Newton and the gravitational law was invented in 1680. As the objects move far from each other the gravitational effect reduces. 

JEE Main is a well-known entrance examination which is conducted on a national level held by the NTA to offer admission to aspirants wanting to seek admission in BE/BTech, BPlan, and BArch courses at the top universities in India. It is a computer-based examination and the duration is 3 hours. Check JEE Main New Pattern

JEE Main Test series - Previous Year Asked Questions and Solutions

1. 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 the earth) is 10 m/s2 and 6400 km respectively. The required energy for this work will be

Options-

(a) 6.4 x 1010 Joules

(b) 6.4 x 1011 Joules

(c) 6.4 x 108 Joules

(d) 6.4 x 109 Joules

Answer: (a) 6.4 x 1010 Joules

2. 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 earth

Options

a) The acceleration of S is always directed towards the centre of the earth

b) The angular momentum of S about the centre of the earth changes in direction but its magnitude remains constant

c) The total mechanical energy of S varies periodically with time

d) The linear momentum of S remains constant in magnitude

Correct Answer: A

3. Q3: An artificial satellite moving in a circular orbit around the earth has a total (K.E. + P.E.) energy E0. Its potential energy is

Options- 

(a) – E0

(b) 1.5 E0

(c) 2 E0

(d) E0

Answer: (c) 2 E0

4. If the distance between the earth and the sun becomes half its present value, the number of days in a year would have been

Options-

A) 64.5

B) 129

C) 182.5

D) 730

Correct Answer: B

5. 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?

Options-

(a) 5GmM/6R

(b) 2GmM/3R

(c) GmM/2R

(d) GmM/3R

Answer: (a) 5GmM/6R

6. A satellite is moving with a constant speed ‘V’ 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.

Options-

(a)1/2 mV2

(b) mV2

(c) 3/2 mV2

(d)2 mV2

Answer: (b) mv2

7. 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?

Options-

(a) 5GmM/6R

(b) 2GmM/3R

(c) GmM/2R

(d) GmM/3R

Answer: (a) 5GmM/6R

8. 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 the second satellite is larger than that of the first one by approximately

Options- 

A) 0.5%

B) 1.0%

C) 1.5%

D) 3.0%

Correct Answer: C

9. 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

Options-

(a) R/2

(b) R/3

(c) 2R

(d) 3R

Answer: (c) 2R

10. A simple pendulum has a period T1 when on the earth’s surface, and T2 when taken to a height R above the earth’s surface, where R is the radius of the earth. The value of T2/T1 is

Options- 

(a) 1

(b) 3

(c) 4

(d) 2

Answer: (d) 2

     11. 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 the second satellite is larger than that of the first one by approximately

Options-

A) 0.5%

B) 1.0%

C) 1.5%

D) 3.0%

Correct Answer: C

      12. Two bodies of masses m and 4m are placed at a distance r. The gravitational field is zero is where the potential of a gravitational force at a point on the line joining them should be: 

Options- 

(a) -6Gm/r

(b) -9Gm/r

(c) Zero

(d) -4Gm/r

Answer: (b) -9Gm/r

     13. A particle is moving with a uniform speed in a circular orbit of radius R in a central force inversely proportional to the nth power of R. If the period of rotation of the particle is T, then

Options-

(a) T ∝ R3/2

(b) T ∝ R(n/2)+1

(c) T ∝ R(n+1)/2

(d) T ∝ Rn/2

Answer: (c) T ∝ R(n+1)/2

      14. Suppose that the angular velocity of rotation of the earth is increased. Then, as a consequence

Options-

(a) There will be no change in weight anywhere on the earth

(b) Weight of the object, everywhere on the earth, will increase

(c) Except at poles, the weight of the object on the earth will decrease

(d) Weight of the object, everywhere on the earth, will decrease.

Answer: (c) Except at poles, the weight of the object on the earth will decrease

      15. 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 earth

Options-

A) The acceleration of S is always directed towards the centre of the earth

B) The angular momentum of S about the centre of the earth changes in direction but its magnitude remains constant

C) The total mechanical energy of S varies periodically with time

D) The linear momentum of S remains constant in magnitude

Correct Answer: A

Quick Formulas For Revision

1. Gravitational force-

2. Acceleration due to gravity (g)

 

3. Variation in 'g' with height

4. Variation in 'g' with depth

5. Variation in 'g' due to Rotation of earth

6. Gravitational field Intensity

Where F=Gravitational force

7. Gravitational Potential

or

8. Work was done against gravity

9. Escape velocity

10. Escape energy

11. Kepler's 2nd law

12. Kepler's 3rd law

or