when a child sits stationary at one end of a long trolley moving uniformly with some speed on a smooth horizontal plane. The speed of the centre of mass of system (child and trolley),

when a child sits stationary at one end of a long trolley moving unifo

1.	when a child sits stationary at one end of a long trolley moving uniformly with some speed on a smooth horizontal plane. The speed of the centre of mass of system (child and trolley),
Answer» Solution :No change in SPEED of SYSTEM as no EXTERNAL force is working