Chapter–8: Gravitation Assertion Reason

These questions of two statements each, printed as Assertion and Reason. While answering these Questions you are required to choose any one of the following four responses.

(A) If both Assertion & Reason are true & the Reason is a correct explanation of the Assertion.

(B) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion.

(C) If Assertion is true but the Reason is false.

(D) If Assertion & Reason both are false.

Q.1 Assertion : A geostationary satellite rotates in a direction from west to east.

Reason : At midnight when the sun is directly below, it pulls on an object in the same direction as the pull of the earth on that object. At noon when the sun is directly above, it pulls on an object in a direction opposite to the pull of the earth.

(1) A (2) B (3) C (4) D

Answer:2

Q.2 Assertion : The acceleration of a particle near the earth surface differs slightly from the gravitational acceleration a_g = GM/R².

Reason : The earth is not a uniform sphere and because the earth rotates.

(1) A (2) B (3) C (4) D

Answer:1

Q.3 Assertion : If the earth stops rotating about its axis. The value of the weight of the body at equator will decrease.

Reason : The centripetal force will not acting on the body at the equator.

(1) A (2) B (3) C (4) D

Answer:4

Q.4 Assertion : Gravitational potential is maximum at infinite.

Reason : Gravitational potential is the amount of work done to shifting a unit mass from infinity to a given point in gravitational attraction force field.

(1) A (2) B (3) C (4) D

Answer:1

Q.5 Assertion : Two satellites A and B are in the same orbit around the earth, B being behind A. B cannot overtake A by increasing its speed.

Reason : It will then go into a different orbit.

(1) A (2) B (3) C (4) D

Answer:1

Q.6 Assertion : Kepler’s law of areas is equivalent to the law of conservation of angular momentum.

Reason : = = constant

(1) A (2) B (3) C (4) D

Answer:1

Q.7 Assertion : For circular orbits, the law of periods is T² = , where M is the mass of sun.

Reason : The square of the period T of any planet about the sun is proportional to the cube of the semi-major axis a of the orbit.

(1) A (2) B (3) C (4) D

Answer:1

Q.8 Assertion : A person feels weightlessness in an artificial satellite of the earth. However a person on the moon (natural satellite) feels his weight.

Reason : Artificial satellite in a freely falling body and on the moon surface, the weight is mainly due to moon’s gravitational attraction.

(1) A (2) B (3) C (4) D

Answer:1

Q.9 Assertion : Kepler’s law of areas is equivalent to the law of conservation of angular momentum.

Reason : = = constant

(1) A (2) B (3) C (4) D

Q.10 Assertion : If rotation of earth is suddenly stops then acceleration due to gravity will increase at all places on the earth.

Reason : At height h from the surface of earth, acceleration due to gravity is g_h = .

(1) A (2) B (3) C (4) D

Answer:4

Q.11 Assertion : Earth is continuously pulling moon towards its centre but moon does not fall to earth.

Reason : Attraction of sun on moon is greater than that of earth on moon.

(1) A (2) B (3) C (4) D

Answer:3Assertion-Reason Questions and Answers

Chapter 8: Gravitation

Assertion (A): The gravitational force between two point masses is always attractive.
Reason (R): The gravitational force is given by Newton’s law of gravitation.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The value of the gravitational constant (G) depends on the nature of the medium between the masses.
Reason (R): The gravitational constant (G) is a universal constant.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (d) Assertion (A) is false but Reason (R) is true.
Assertion (A): The acceleration due to gravity decreases with altitude.
Reason (R): The acceleration due to gravity is inversely proportional to the square of the distance from the center of the Earth.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The escape velocity from the surface of the Earth is independent of the mass of the object.
Reason (R): The escape velocity depends only on the mass and radius of the Earth.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): Satellites in geostationary orbit appear stationary relative to an observer on Earth.
Reason (R): The orbital period of a geostationary satellite is equal to the rotational period of the Earth.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): Gravitational potential energy is always negative.
Reason (R): Gravitational potential energy is zero at infinite separation between two masses.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The gravitational force inside a uniform spherical shell is zero at any point.
Reason (R): A uniform spherical shell produces a gravitational field equivalent to that of a point mass at its center for external points.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The orbital speed of a satellite in a circular orbit depends on its mass.
Reason (R): The gravitational force provides the necessary centripetal force for the satellite’s motion.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (d) Assertion (A) is false but Reason (R) is true.
Assertion (A): The gravitational force between two masses increases if the distance between them is halved.
Reason (R): The gravitational force is inversely proportional to the square of the distance between the masses.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The gravitational potential at a point is always negative.
Reason (R): Gravitational potential is defined as the work done by an external force in bringing a unit mass from infinity to that point.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The gravitational potential energy of a system of masses is always negative.
Reason (R): Gravitational potential energy is zero at infinite separation between masses.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The orbital speed of a satellite is independent of its mass.
Reason (R): The gravitational force provides the necessary centripetal force for the satellite’s motion.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The gravitational force between two point masses is directly proportional to the product of their masses.
Reason (R): Newton’s law of gravitation states that the force between two point masses is proportional to the product of their masses and inversely proportional to the square of the distance between them.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The escape velocity from a planet is higher if the planet has a larger mass.
Reason (R): Escape velocity is proportional to the square root of the mass of the planet and inversely proportional to the square root of its radius.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): A satellite in a higher orbit has a lower orbital speed compared to one in a lower orbit.
Reason (R): The orbital speed of a satellite is inversely proportional to the square root of the radius of its orbit.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): Gravitational force is a central force.
Reason (R): Gravitational force acts along the line joining the centers of the two masses.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The gravitational force between two objects becomes zero if the distance between them is infinite.
Reason (R): According to Newton’s law of gravitation, the force between two masses is inversely proportional to the square of the distance between them.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The gravitational potential energy of a system of two masses is inversely proportional to the distance between them.
Reason (R): Gravitational potential energy is given by the formula \(U = -\frac{Gm_1m_2}{r}\), where \(r\) is the distance between the masses.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The gravitational field inside a hollow spherical shell is zero.
Reason (R): The gravitational force inside a hollow spherical shell is zero.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The orbital period of a satellite is independent of its mass.
Reason (R): The orbital period of a satellite depends only on the mass of the planet and the radius of the orbit.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The escape velocity from the Moon is less than that from the Earth.
Reason (R): The Moon has less mass and a smaller radius than the Earth.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The gravitational potential energy of a system of two masses is negative.
Reason (R): Gravitational potential energy is defined as the work done to assemble the system from infinite separation.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
Assertion (A): The gravitational force between two masses is zero if one of the masses is zero.
Reason (R): Gravitational force is directly proportional to the product of the masses.
- (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- (b) Both Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- (c) Assertion (A) is true but Reason (R) is false.
- (d) Assertion (A) is false but Reason (R) is true.
Answer: (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

Chapter–8: Gravitation Assertion Reason

Chapter–8: Gravitation Assertion Reason

Chapter 8: Gravitation

Chapter–7: System of Particles and Rotational Motion Assertion Reason

Chapter–9: Mechanical Properties of Solids Assertion Reason