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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? |
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Answer» <P> Solution :(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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