Question

A boy of mass 40kg climbs up the stairs and reaches the roof at a height 8m in 5s.Calculate :

1-the force of gravity acting on the boy

2-the work done by him against the gravity

3-the power sent by the boy

(take g=10m 1/s²)

Answer 1

Force of gravity acting on the boy = mg
= 40 * 10
= 400 N

(ii)
here H=8
meter
Work done by him = mgh
= 40 * 10 * 8
= 3200 J

(iii)
Power = Work / Time
= 3200 / 5
= 640 Watt