In physics, Hooke's law of elasticity is an approximation that states that the amount by which a material body is deformed (the strain) is linearly related to the force causing the deformation (the stress). Materials for which Hooke's law is a useful approximation are known as linear-elastic or "Hookean" materials.
Hooke's law is named after the 17th century British physicist Robert Hooke. He first stated this law in 1676 as an anagram, then in 1678 in Latin as Ut tensio, sic vis, which means:
When this holds, we say that the behavior is linear. If shown on a graph, the line should show a direct variation.