A $14.5\; kg$ mass, fastened to the end of a steel wire of unstretched length $1.0 \;m ,$ is whirled in a vertical circle with an angular velocity of $2\;rev/s$ at the bottom of the circle. The cross-sectional area of the wire is $0.065 \;cm ^{2} .$ Calculate the elongation of the wire when the mass is at the lowest point of its path.

In which case there is maximum extension in the wire, if same force is applied on each wire

The following four wires are made of same material. Which one will have the largest elongation when subjected to the same tension ?

A $100\,m$ long wire having cross-sectional area $6.25 \times 10^{-4}\,m ^2$ and Young's modulus is $10^{10}\,Nm ^{-2}$ is subjected to a load of $250\,N$, then the elongation in the wire will be :

An equilateral triangle $ABC$ is formed by two copper rods $AB$ and $BC$ and one is aluminium rod which heated in such a way that temperature of each rod increases by $\Delta T$. Find change in the angle $\angle {ABC}$. (Coefficient of linear expansion for copper is $\alpha _1$ and for aluminium is $\alpha _2$).