$A$ wire of density $3 \times 10^3 \, kg/m^3$ requires a breaking stress of $10^6 \, N/m^2$ to break. What should be the length of the wire so that it breaks under its own weight? (Take $g = 10 \, m/s^2$)

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 $k = \frac{YA}{L}$]

Match the following:

Column $I$	Column $II$
$A$. Hooke's law	$1$. Tangential strain
$B$. Shearing strain	$2$. Temporary loss of elastic property
$C$. Bulk strain	$3$. Elastic limit
$D$. Elastic fatigue	$4$. $3$ times the linear strain

$A$ wire of length $5 \,m$ is twisted through $30^{\circ}$ at its free end. If the radius of the wire is $1 \,mm$,the shearing strain in the wire is: (in $^{\circ}$)

The two thigh bones (femurs),each of cross-sectional area $10 \; cm^{2}$,support the upper part of a human body of mass $40 \; kg$. Estimate the average pressure sustained by the femurs.

Due to the addition of impurities,the modulus of elasticity