Concepts of Physics

IIT JEE Physics (1978-2018: 41 Years) Topic-wise Complete Solutions

Spring Potential Energy


To study potential energy of a spring.


Toy car with spring mechanism, scale, chalk


Take a toy car with a spring mechanism. Make a mark on a uniform floor with a chalk. Wind the key of the car through half a turn, and place the toy at the mark on the floor. Make another chalk mark at the point where the car stops. Measure the distance \(x\) between the two marks. This is the distance moved by the car. Rub out the second mark.


Now, wind the key through a full turn and place it at the first mark. Measure the distance the car moves before stopping. Repeat the experiment for one and a half turns of the key and two turns of the key. Measure the value of \(x\) in each case.

The greater the number of turns, the larger is the distance travelled by the car. This is because when the spring is compressed more, it stores more energy. The distance \(x\) is roughly proportional to the energy stored in the spring. Try to get the relation between the energy stored and the number of turns of the key.