Hooke's law

Law stating that the deformation of a body is proportional to the magnitude of the deforming force, provided that the body's elastic limit (see elasticity) is not exceeded. If the elastic limit is not reached, the body will return to its original size once the force is removed. The law was discovered by English physicist Robert Hooke in 1676.

A force applied to a spring by adding a weight to it will cause the spring to stretch in proportion to the applied force. If the force is removed and the spring returns to its original size, the material of the spring is said to be elastic. If the spring does not return to its original size, the material is said to be non-elastic. The elastic limit is the maximum amount of force that can be applied without deforming the material to the point at which it becomes non-elastic.

For example, if a spring is stretched by 2 cm by a weight of 1 N, it will be stretched by 4 cm by a weight of 2 N, and so on. However, once the load exceeds the elastic limit for the spring, Hooke's law will no longer be obeyed and each successive increase in weight will result in a greater extension until finally the spring breaks.