A child is standing at one end of a long trolley moving with a speed v on a smooth horizontal track.
Channel: Doubtnut
Date: 2021-11-02

A child is standing at one end of a long trolley moving with a speed v on a smooth horizontal track. If the child starts running towards the other end of the trolley with a speed u, the centre of mass of the system (trolley + child) will move with a speed :