A spring is kept compressed by a small trolley of mass 0.5 kg 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 2 ms-1. What potential energy did the spring possess when compressed?
1 J
On releasing the trolley, the spring tries to come back to its uncompressed state by pushing the trolley away. Thus, the potential energy stored in the spring changes into the kinetic energy of trolley.
Potential energy = Kinetic energy
= 1/2mv2
= 1/2 x 0.5 x 22
= 1/2 x 0.5 x 4
= 1 joule