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?
ScienceClass 9CBSEAnswered 27 Mar 2026
Answer
(a)
Initial velocity of the trolley,u = 4 m/s Final velocity of the trolleyv = 0 Mass of the trolleym = 5 kg
Distance covered by the trolley before coming to rest,s = 16 m From Equation 2 as =v2-u2,
a = v2-u22 S
=0-(4)22x16
=0.5 m/s2
Force (frictional) acting on the trolley = ma
= 40 (- 0.5)
= - 20 N
Work done on the trolley = Fs = (20 N) (16 m)
= 320 J
(b) Since the girl does not move w.r.t. the trolley (as she is sitting on it),work done by the girl = 0.
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