a boy lifts a 5 kg box from ground and places it on his head in 2 seconds.if height of boy is 1.25 m then:
1.find the work done by the boy in lifting the box
2.find the power used by boy in lifting the box
3.what will be the work done by gravity in this case?

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Solution

$W o r k d o n e = m g h W = 5 \times 9.81 \times 1.25 W = 61.3125 J P o w e a p p l i e d = \frac{W o r k}{T i m e} = \frac{61.3125}{2} = 30.6563 W$

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