Question

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.

Answer 1

A) Young’s modulus of any material is given by
$Y=\frac{\text{Stress}}{\text{Strain}}$
For a given stress,$Y\propto \frac{1}{\text{strain}}$
For given stress, the strain in rubber is more than in steel. Therefore,

$Y_R<Y_S$

$\therefore$ The statement “Young’s modulus of rubber is greater than that of steel“ is $\text{false}$



B) Shear modulus is the ratio of shear stress to the shear strain.

While stretching the coil, the wire gets twisted, but it itself remains unstretched.

Hence, stretching of a coil is determined by its shear modulus and not Young’s modulus.

$\therefore$ The statement “The stretching of a coil is determined by its shear modulu'' is true.