A spring is suspended from a rigid support as shown in the Figure. A weight hanger and a light pointer is attached at its lower end such that the pointer can slide over a scale graduated in millimeters.

The initial reading on the scale is noted. A slotted weight of m kg is added to the weight hanger and the pointer position is noted. The same procedure is repeated with every additional m kg weight. It will be observed that the extension of the spring is proportional to the weight. This verifies Hooke’s law.

Hooke’s Law Formula is given by: F = -kx

Example: A spring is stretched by 5 cm and has force constant of 2 cm /dyne. Calculate the Force applied?

Given: Force constant k = 2 cm/dyne,

Extension x = 5 cm.

The force applied is given by F = – kx = – 2cm/dyne * 5 cm = – 10 cm/dyne.