Hooke's Law (Stress-Strain Relation) (stress = k × strain)

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stress = k × strain

What each symbol means

SymbolWhat it stands for
kModulus of elasticity (Pa)
strainFractional change in dimension (dimensionless)
stressRestoring force per unit area (N m⁻² or Pa)

When to use this

Valid only within the elastic limit (linear region OA of stress-strain curve). Beyond yield point, relationship is non-linear. Elastomers like rubber do not obey Hooke's law. Stress = F/A where F is applied force and A is cross-sectional area.