State Hook's law:

Sol.: It states that when material is loaded within the elastic limit, the stress is proportional to strain produced by the stress. This means that the ratio of the stress to the corresponding strain is constant within the elastic limit. This constant is called as Modulus of Elasticity or Modulus of Rigidity.

Stress /strain = constant

The constant is called as elastic constant

Normal stress/ Normal strain = Young's modulus or Modulus of elasticity (E) Shear stress/ Shear strain  = Shear modulus or Modulus of Rigidity (G)

Direct stress/ Volumetric strain = Bulk modulus (K)