Question

A 50 kg girl is swinging on a swing from rest. Then, the power delivered when moving with a velocity of 2 $m{s}^{-1}$ upwards in a direction making an angle ${60}^0$ with the vertical is?

• A. 980 W
• B. 490 W
• C. $490\sqrt{3}$ W
• D. 245 W

Answer 1

Answer: (B)

. 490 W.

We know that,

Power = Tension $\times$ Velocity

$P=T\times v$

$T=F\cos \theta =mg\cos \theta =50\times 9.8\times \cos 60$

$v=2m/s$ (Given)

$\therefore P=(50\times 9.8\times \cos 60)\times 2$

$\Rightarrow P=490W$.