
Q4 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. Ans: (a) False (b) True
(a) For a given stress, the strain in rubber is more than it is in steel.
Young’s modulus, Y = stress / strain
For a constant stress: Y ∝ 1 / strain
Hence, Young’s modulus for rubber is less than it is for steel.
(b) Shear modulus is the ratio of the applied stress to the change in the shape of a body. The stretching of a coil changes its shape. Hence, shear modulus of elasticity is involved in this process.