Question

When a particle is rotating in a circle will happen:

• A. no force is acting on particle
• B. velocity of particle is constant
• C. particle has no acceleration
• D. no work is done

Answer 1

Answer: (D)

no work is done

Answer 2

We know that when a particle is rotating on a circular path, a centripetal force $\overrightarrow{{{F}_{c}}}$ exists on the rotating parallel. Instantaneous translational displacement ${{\overrightarrow{d}}_{s}}$ is always $90{}^\circ$ throughout its motion. Thus work done $W=\overrightarrow{F}\cdot {{\overrightarrow{d}}_{s}}=Fds\,\cos 90{}^\circ =0\,\,(zero)$