A boy of mass `m` is standing on a platform of `M` kept on smooth floor. If the body starts moving on the platform with a speed `v_(0)` relative to the platform , with what velocity to the floor does the platform recoil ?

Explanation

`v_(0) : v_(B//P)` : velocity of boy relative to platform
`v : v_(p//g)` : velocity of platform relative to ground
`v_(B//g) = v_(0) - v`
By the momentum conservation
`0 = m(v_(0) - v) - Mv`
`v = (mv_(0))/(M + m)`