Question

A boy of mass 60 kg running at 3 m/s jumps on to a trolley of mass 140 kg moving with velocity of 1.5 m/s in the same direction. With what velocity will the two moves together?​

Answer 1

Answer:

This question is based on conservation of momentum...

initial momentum= final momentum..

common velocity means both trolley and boy moves with same velocity..

initial momentum=60×3+140×1.5

=180 + 210

=390 kg m/s

final momentum=(60+140)V

200V

so on equating..

200V=390

V=390/200=1.95m/s...

Answer 2

Answer:

Here, `m_(1)=60 kg , u_(1) = 3m//s, m_(2)= 140 kg , u_(2) = 1.5m//s`

if `v` is their common velocity, then applying the principle of conservation of linear momentum, we get

`m_(1)u_(1)+m_(2)u_(2)= (m_(1)+m_(2))v` or `60xx3+140xx1.5= (60+140)v`

or `180+210= 200v` or `v=(390)/(200)= 1.95m//s