Hooke's Law

A Law stating that, in a linear system, the restoring force is proportional to the displacement of the body, acting in a direction as to restore equilibrium.


F = restoring force [N]
k = spring constant [Nm-1]
x = elongation of material [m]

A material such as copper, when stretched beyond it's elastic limit it retains it's shape.

A material such as rubber, this does not follow Hooke's law and remains elastic until it snaps.

A material such as glass, this follows Hooke's law until it snaps.

The constant of that proportionality is the Young modulus of elasticity for that substance.

E = Young's modulus [Nm-2]
F = applied load [N]
A = cross-sectional area [m2]
x = extension [m]
L = original length [m]

Enter values into 4 of the 5 fields. The others will be calculated.

Stress-Strain curve for a material such as mild steel.

Hooke's Law would apply within the linear region up to the elastic limit of the material.

See also: Elasticity, Force, Simple Harmonic Motion, Spring Constant, Strain, Stress.

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Subjects: Mechanical Engineering