Definition: It is defined (is the ratio of shear stress to shear strain within elastic limit.
It is denoted by ‘n’.
Unit: N/m2 or Pa in SI system.
Dimension: [L-1M1T-2]
Expression for modulus of rigidity:
Consider a solid cube as shown in the figure.
Let, F = Tangential force
A = Cross sectional area
∆l = Relative displaced length
l = Original length
θ = Shear strain
[Note: Displacement of upper surface is exaggerated for explanation.]
The forces applied on the block is subjected to a shear stress,
Shearing stress = F/A
The comer angle which changes by a small amount θ (expressed in radian) is given by,
Shearing strain = \(\frac{\triangle l}{l}\) ≈ θ
From definition,
