Question

A spring is kept compressed by a small trolley of mass 0.5kg lying on a smooth horizontal surface as shown in the figure given below : 

When the trolley is released, it is found to move at a speed of 2ms^-1.

What potential energy did the spring possess when compressed?

Answer 1

When spring is compressed, there is a potential energy stored in it. When the trolley is released the potential energy of spring is converted into kinetic energy of the trolley