question_answer

Assertion (A) If there is no external torque on a body about its centre of mass, then the velocity of the centre of mass remains constant. Reason (R) The linear momentum of an isolated system remains constant. Each of these questions contains two statements. Assertion and Reason. Each of these questions also has four alternative choices, only one of-which is the correct answer. You have to select one of the codes (a), (b), (c) and (d) given below.

A) If both Assertion and Reason are true and Reason is 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: D

Solution :

Assertion is false, reason is true. If a force is applied at the centre of mass of a rigid body, its torque about centre of mass will be zero but acceleration will be non-zero. Hence, velocity will change.