Question

A man of mass m is standing on a plank of equal mass m resting on a smooth horizontal surface. The man starts moving on the plank with speed u relative to the plank. The speed of the man relative to the ground is

A. 2u
B. `u/2`
C. zero
D. `u/4`

Answer 1

Correct Answer - B
`m(u-v) = mv`
`therefore v=(u)/(2)`

`therefore` Velocity of man relative to ground = u-v=u/2`