Power in Uniform Circular Motion – Rankers Physics

Work Done by Constant and Variable Forces: Practice Problem & Solution

Assertion (A): Power delivered by all forces acting on a particle moving in a uniform circular motion is always zero. Reason (R): Work done by all forces acting on a particle moving in a uniform circular motion is zero as KE remains constant.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Work Done by Constant and Variable Forces. Understanding the underlying formula is key to arriving at the correct answer below:

Assertion (A) is true: In uniform circular motion, the net force (centripetal force) is always perpendicular to the velocity. Power \(P = F \cdot v = |F||v| \cos 90^\circ = 0\). Reason (R) is true: Since speed is constant, kinetic energy \(KE\) is constant, thus \(Delta KE = 0\). By the Work-Energy Theorem, net work done \(W_{net} = \Delta KE = 0\). Reason (R) correctly explains why power is zero.

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