Ncert Exercises & Solutions

9.4 Read the following two statements below carefully and state, with reasons, if it is true or false.

(a) The Young’s modulus of rubber is greater than that of steel;

(b) The stretching of a coil is determined by its shear modulus.

9a) The strain in rubber is more than that in steel for a given stress.

For the same stress: $Y \propto \frac{1}{Strain}$

Hence, Young’s modulus for rubber is less than that for steel.

(b) The ratio of the applied stress to the change in the shape of a body is known as the shear modulus.

The stretching of a coil changes its shape. Hence, shear modulus determines the elasticity of the coil in this process.