$A$ uniform wire (Young's modulus $2 \times 10^{11} \, Nm^{-2}$) is subjected to a longitudinal tensile stress of $5 \times 10^7 \, Nm^{-2}$. If the overall volume change in the wire is $0.02\%$,the fractional decrease in the radius of the wire is close to:

Which of the following affects the elasticity of a substance?

In the given figure,two elastic rods $A$ and $B$ are rigidly joined to end supports. $A$ small mass $m$ is moving with velocity $v$ between the rods. All collisions are assumed to be elastic and the surface is frictionless. The time period of the small mass $m$ will be: [Here,an elastic rod may be treated as a spring of spring constant $k = \frac{YA}{L}$]

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.

For the tensile stress on the cross-section $PQRS$ to be maximum,$\theta =$ ......... $^o$

$A$ string $AB$ of unstretched length $L$ is stretched by applying a force $F$ at the mid-point $C$ such that the segments $AC$ and $BC$ make an angle $\theta$ with $AB$ as shown in the figure. The string may be considered as an elastic element with a force to elongation ratio $K$. The force $F$ is given by