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A 50 kg girl is swinging on a swing from...

A 50 kg girl is swinging on a swing from rest. Then, the power delivered when moving with a velocity of `2ms^(-1)` upwards in a direction making an angle `60^(@)` with the vertical is

A

980 W

B

490 W

C

`490sqrt3`

D

245 W

Text Solution

Verified by Experts

The correct Answer is:
C
(c ) Two force are acting on girl, tension and weight. Power of tension will be zero and that of weight is,

`P=mgv cos(90^(@)+theta)=-"mg v sin" 60^(@)`
`=-50xx9.8xx2xx(sqrt3)/(2)=-490sqrt3W`
`:. "Power delivered is " 490sqrt3W`.
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