Chapter 7: Gravitation Assertion-Reason Questions | physics Class 11 CBSE

Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 1

Logic Check

Assertion (A): All planets move in circles with the Sun at the centre. Reason (R): The gravitational force between the Sun and a planet is an inverse-square central force.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 2

Logic Check

Assertion (A): A planet moves faster when it is nearer to the Sun. Reason (R): The gravitational force on the planet increases as it comes closer to the Sun.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 3

Logic Check

Assertion (A): The square of the time period of a planet is proportional to the cube of its semi-major axis. Reason (R): This relationship holds only for planets in circular orbits.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 4

Logic Check

Assertion (A): The gravitational force between two bodies is always attractive. Reason (R): Gravitational force obeys Newton's third law, so forces are equal and opposite.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 5

Logic Check

Assertion (A): Cavendish's experiment is often described as 'weighing the Earth'. Reason (R): Cavendish directly measured the mass of the Earth in his experiment.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 6

Logic Check

Assertion (A): Acceleration due to gravity increases as we go deeper below the Earth's surface. Reason (R): At depth d, only the inner sphere of radius (RE - d) contributes to gravitational force.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 7

Logic Check

Assertion (A): Acceleration due to gravity is maximum at the surface of the Earth. Reason (R): The Earth exerts maximum gravitational force at the surface.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 8

Logic Check

Assertion (A): Gravitational potential energy is negative for any mass near the Earth. Reason (R): The gravitational force is repulsive in nature.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 9

Logic Check

Assertion (A): The total energy of a satellite in a circular orbit is negative. Reason (R): The gravitational potential energy of the satellite is positive.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 10

Logic Check

Assertion (A): Escape speed from the surface of the Earth does not depend on the angle of projection. Reason (R): The escape speed formula ve = √(2gRE) does not contain any angle term; energy conservation is independent of direction.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 11

Logic Check

Assertion (A): An astronaut in a space satellite feels weightless. Reason (R): The gravitational force on the astronaut is zero at the satellite's altitude.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 12

Logic Check

Assertion (A): The Moon has a thick atmosphere similar to Earth's. Reason (R): The escape speed from the Moon (approx 2.3 km/s) is too small to retain gas molecules, which escape into space.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 13

Logic Check

Assertion (A): A hollow spherical shell does not exert any gravitational force on a point mass inside it. Reason (R): The net gravitational force on the interior mass due to all parts of the shell cancels to zero by symmetry.

Reasoning Options

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Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 14

Logic Check

Assertion (A): Gravitational shielding is not possible. Reason (R): The shell theorem proves that the force inside a uniform spherical shell is always zero.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 15

Logic Check

Assertion (A): As a satellite is moved to a higher circular orbit, its orbital speed decreases. Reason (R): Orbital speed V = √(GME/r) decreases as r increases.

Reasoning Options

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Assertion-Reason

Easy difficulty • Check the statement and reason

Easy

Question 16

Logic Check

Assertion (A): A geostationary satellite has a time period of 24 hours. Reason (R): All satellites orbiting the Earth have a time period of 24 hours.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 17

Logic Check

Assertion (A): The time period of a satellite increases as it is placed in a higher orbit. Reason (R): A satellite in a higher orbit has greater total mechanical energy.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 18

Logic Check

Assertion (A): The total potential energy of a system of particles is the sum of potential energies of all possible pairs. Reason (R): This follows from Newton's third law of motion.

Reasoning Options

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Assertion-Reason

Hard difficulty • Check the statement and reason

Hard

Question 19

Logic Check

Assertion (A): When a satellite loses energy due to atmospheric drag, it spirals to a lower orbit and moves faster. Reason (R): In a lower orbit, the gravitational force on the satellite decreases.

Reasoning Options

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Assertion-Reason

Medium difficulty • Check the statement and reason

Medium

Question 20

Logic Check

Assertion (A): The gravitational force between the Earth and Moon acts along the line joining their surfaces. Reason (R): For spherically symmetric bodies, the gravitational force acts along the line joining their centres.

Reasoning Options

ByteNotes

Chapter sections

Chapter 7: Gravitation | Assertion-Reason

Assertion (A): All planets move in circles with the Sun at the centre. Reason (R): The gravitational force between the Sun and a planet is an inverse-square central force.

Assertion (A): A planet moves faster when it is nearer to the Sun. Reason (R): The gravitational force on the planet increases as it comes closer to the Sun.

Assertion (A): The square of the time period of a planet is proportional to the cube of its semi-major axis. Reason (R): This relationship holds only for planets in circular orbits.

Assertion (A): The gravitational force between two bodies is always attractive. Reason (R): Gravitational force obeys Newton's third law, so forces are equal and opposite.

Assertion (A): Cavendish's experiment is often described as 'weighing the Earth'. Reason (R): Cavendish directly measured the mass of the Earth in his experiment.

Assertion (A): Acceleration due to gravity increases as we go deeper below the Earth's surface. Reason (R): At depth d, only the inner sphere of radius (RE - d) contributes to gravitational force.

Assertion (A): Acceleration due to gravity is maximum at the surface of the Earth. Reason (R): The Earth exerts maximum gravitational force at the surface.

Assertion (A): Gravitational potential energy is negative for any mass near the Earth. Reason (R): The gravitational force is repulsive in nature.

Assertion (A): The total energy of a satellite in a circular orbit is negative. Reason (R): The gravitational potential energy of the satellite is positive.

Assertion (A): Escape speed from the surface of the Earth does not depend on the angle of projection. Reason (R): The escape speed formula ve = √(2gRE) does not contain any angle term; energy conservation is independent of direction.

Assertion (A): An astronaut in a space satellite feels weightless. Reason (R): The gravitational force on the astronaut is zero at the satellite's altitude.

Assertion (A): The Moon has a thick atmosphere similar to Earth's. Reason (R): The escape speed from the Moon (approx 2.3 km/s) is too small to retain gas molecules, which escape into space.

Assertion (A): A hollow spherical shell does not exert any gravitational force on a point mass inside it. Reason (R): The net gravitational force on the interior mass due to all parts of the shell cancels to zero by symmetry.

Assertion (A): Gravitational shielding is not possible. Reason (R): The shell theorem proves that the force inside a uniform spherical shell is always zero.

Assertion (A): As a satellite is moved to a higher circular orbit, its orbital speed decreases. Reason (R): Orbital speed V = √(GME/r) decreases as r increases.

Assertion (A): A geostationary satellite has a time period of 24 hours. Reason (R): All satellites orbiting the Earth have a time period of 24 hours.

Assertion (A): The time period of a satellite increases as it is placed in a higher orbit. Reason (R): A satellite in a higher orbit has greater total mechanical energy.

Assertion (A): The total potential energy of a system of particles is the sum of potential energies of all possible pairs. Reason (R): This follows from Newton's third law of motion.

Assertion (A): When a satellite loses energy due to atmospheric drag, it spirals to a lower orbit and moves faster. Reason (R): In a lower orbit, the gravitational force on the satellite decreases.

Assertion (A): The gravitational force between the Earth and Moon acts along the line joining their surfaces. Reason (R): For spherically symmetric bodies, the gravitational force acts along the line joining their centres.

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