Question

1. 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.​

Answer 1

$\huge\underline\mathrm\pink{Answer}$

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

Answer 2

Answer:

Work done on trolley W = FS = 20 N x 16 = 320 J

Work done by the girl, = mass of girl × retardation × S

= 35 × 0.5 × 16

= 280 J