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CBSE Class 9 Answered

a girl having a mass of 35kg sits on a trolley of mass 5 kg. the trolley is given an initial velocity of 4m/s by applying a force. the trolley comes to rest after travelling a distance of 16m. how much work is done on the trolley? how much work is done by the girl?
Asked by Saranya Krishnamurthy | 15 Feb, 2014, 04:43: PM
answered-by-expert Expert Answer

Given:

Mass of girl = 35 kg

Mass of trolley = 5 kg

Total mass, m = (35 + 5) = 40 kg

 u = 4 m/s

v = 0

s = 16 m

By equation,

v 2 = u 2 + 2as

0 = (4)2 + 2a (16)

32a = –16

a = –0.5 m/s2

Force exerted on trolley,

F = ma

   = 40 × 0.5 = 20 N

 

Work done on trolley W = FS = 20 N x 16 m

                                                 = 320 J

Work done by the girl, W = FS

                                          = mass of girl × retardation × S

                                          = 35 × 0.5 × 16

                                          = 280 J
Answered by | 17 Feb, 2014, 09:07: AM

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