Question

Assertion (A) The speed of a body in uniform circular motion is constant.
Reason (R) In uniform circular motion, the acceleration of the body is constant.

• 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

Answer 1

Answer: (C)

(i) Assertion is correct : In uniform circular motion, body moves with constant speed. It is magnitude of velocity, which is constant.
(ii) Reason is incorrect : In uniform circular motion, direction of acceleration (centripetal) is always along the centre, which keep changing when particle moves. As, acceleration is vector quantity and its direction is changing, so it can not be constant.