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Two girls, each of weight 400 N climb up...

Two girls, each of weight 400 N climb up a rope through a height of 8 m. We name one of the girls A and the other B. Girl A takes 20 s while B takes 50 s to accomplish this task. What is the power expended by each girl?

Text Solution

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(i) Power expended by girl A :
Weight of the girl `mg=400N`
Displacement (height) `h=8m`
Time taken `t=20s`
Power `P=("Work done")/("Time taken")`
`=(mgh)/(t)`
`=(400Nxx8m)/(20s)`
`=160W`
(ii) Power expended by girl B :
Weight of the girl `mg=400N`
Displacement (height) `h=8m`
Time taken `t=50s`
Power `P=(mgh)/(t)`
`=(400Nxx8m)/(50s)=64W`
Power expended by girl A is 160 W.
Power expended by girl B is 64 W.
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