AIIMS2018Physics-Rotational Motion

AIIMS 2018 Physics Torque MCQ Question

Type: MCQ-conceptual-Medium-Class 11

Assertion: Torque on a body can be zero even if there is a net force on it.

Reason: Torque and force on a body are always perpendicular.

A

If both assertion and reason are true and reason is the correct explanation of assertion.

B

If both assertion and reason are true but reason is not the correct explanation of assertion.

C

If assertion is true but reason is false.

D

If both assertion and reason are false.

Correct Answer

Option B

Detailed Explanation

Torque (τ) is calculated using the formula τ = r × F × sin(θ), where r is the moment arm (the perpendicular distance from the axis of rotation to the line of action of the force), F is the applied force, and θ is the angle between the force and the moment arm. For torque to be zero while a force is applied, either the moment arm must be zero (option C) or the force must be zero (option B). Option A is incorrect because if the line of action of the force passes through the axis of rotation, the moment arm is zero, leading to zero torque. Option D is also incorrect since an angle of 90° would yield maximum torque, not zero.

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