Question

9.
A boy weighing 40 kgf climbs up a stair of 30 steps each 20 cm high in
4 minutes and a girl weighing 30 kgf does the same in 3 minutes.
(1) The work done by them.
(ii) The power developed by them.
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Answer 1

Work done = Force × displacement.Here in both cases work is done aginst the gravity.W.Dboy=40×9.81 × H (H total distance travelled).W.Dgirl=30×9.81×H distance travelled is same in both the case.W.DboyW.Dgirl=40×9.81 × H 30×9.81×H =43W.DboyW.Dgirl=43In second part we are supposed to find the ratio of there pPower=work done time taken Pboy=40×9.81 × H/4=98.1HPgirl=30×9.81×H /3=98.1HPboyPgirl=1Which means that power by boy and girl are same.

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Answer 2

Explanation:

in pic. bro .......right ans