Previous IIT-JEE Physics Assertion–Reason Questions

Set–4 : Assertion–Reason (Complete Mechanics Coverage)

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Each question has an Assertion (A) and a Reason (R). Choose the correct option:
(A) Both A and R are true and R is the correct explanation of A (B) Both A and R are true but R is not the correct explanation of A (C) A is true but R is false (D) A is false but R is true

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Laws of Motion

Q61.

Assertion (A): A body can move with constant velocity without any external force acting on it.

Reason (R): Force is required only to change the state of motion of a body.

Answer: A

Q62.

Assertion (A): Static friction can be zero.

Reason (R): Static friction is a self-adjusting force.

Answer: A

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Work, Energy and Power

Q63.

Assertion (A): Work done by centripetal force in circular motion is zero.

Reason (R): Centripetal force is always perpendicular to velocity.

Answer: A

Q64.

Assertion (A): Mechanical energy is conserved when friction is present.

Reason (R): Friction is a non-conservative force.

Answer: D

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Centre of Mass

Q65.

Assertion (A): The centre of mass of a system can lie outside the physical body.

Reason (R): Centre of mass depends on mass distribution.

Answer: A

Q66.

Assertion (A): If no external force acts on a system, its centre of mass moves with constant velocity.

Reason (R): Internal forces cancel in pairs.

Answer: B

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Collisions

Q67.

Assertion (A): Momentum is conserved in all types of collisions.

Reason (R): During collision, external impulse is negligible.

Answer: A

Q68.

Assertion (A): Kinetic energy is conserved in perfectly inelastic collisions.

Reason (R): The bodies stick together after collision.

Answer: D

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Rotational Mechanics

Q69.

Assertion (A): Moment of inertia depends on the axis of rotation.

Reason (R): It depends on distribution of mass from the axis.

Answer: A

Q70.

Assertion (A): A rolling body on a rough surface does not lose energy due to friction.

Reason (R): Friction in pure rolling is static.

Answer: B

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Gravitation

Q71.

Assertion (A): Gravitational force between two bodies decreases with distance.

Reason (R): Gravitational force varies inversely as square of distance.

Answer: A

Q72.

Assertion (A): Escape velocity depends on mass of the object.

Reason (R): Gravitational potential energy depends on mass.

Answer: D

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Oscillations & SHM

Q73.

Assertion (A): Time period of SHM is independent of amplitude.

Reason (R): Restoring force is proportional to displacement.

Answer: A

Q74.

Assertion (A): Acceleration is maximum at mean position in SHM.

Reason (R): Displacement is zero at mean position.

Answer: D

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Mechanical Waves

Q75.

Assertion (A): Frequency of a wave depends on the source.

Reason (R): Frequency remains unchanged when wave enters another medium.

Answer: B

Q76.

Assertion (A): Nodes in a standing wave never vibrate.

Reason (R): Amplitude at nodes is always zero.

Answer: A

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✔ End of Previous IIT-JEE Assertion–Reason Questions – Set–4