Question

A ball of $500g$ is suspended by thread of length $50cm$, ball is released when thread makes angle ${60}^{\circ }$. Find power delivered by thread's tension, when thread makes ${30}^{\circ }$ with vertical.

• A. $20\sqrt{3}W$
• B. $40\sqrt{3}W$
• C. Zero
• D. $-20\sqrt{3}W$

Answer 1

The correct option is C Zero

$\overrightarrow{P}=\overrightarrow{F}.\overrightarrow{V}=T.V.\cos {90}^{\circ }=0$
(because $T$ is along radius & $V$ is along tangent)