A man of mass 50 kg starts moving on the earth and acquires speed of 1.8 m/s. With what speed does the earth recoil? Mass of earth =`6xx10^24kg.`

Answer

A

Explanation

A railrod car of ma sM is at rest o frictionless rails when a man of mass m starts movng on the casr towards the engine. The car recoils with a speed v backward on the rails.
Let the mass moving with a velocity x w.r.t the engine.
`:.` The velocity of the mass w.r.t earth is (x-v) towards right.
`V_(CM)=0(Initially at rest)`
`:.-0=-Mv+m(x-v)`
`rarr Mv=m(x-v)`
`rarr mx=Mv+mv`
`rarr x=((M+m)/m)v`
`=(1+M/m)v`