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CBSE - Physics - Work and Energy

Work and Energy

Long Answer Type

A girl having mass of 35 kg sits on a trolley of mass 5 kg. The trolley is given an initial velocity of 4 m s-1 by applying a force. The trolley comes to rest after traversing a distance of 16 m. (a) How much work is done on the trolley? (b) How much work is done by the girl?
Mass of girl = 35 kg, mass of trolley = 5kg, u = 4 m/s, v =0 and s = 16m
(a) Work = F � s = m � a � s
We need to calculate acceleration as follows:



Using the above value of a; work done on trolley can be calculated as follows:
W = mas = 40 � 0.5 � 16 = 320 J
(b) In this case, the girl is not applying any force and so work done by girl = 0
.