A rod of length $l$ and radius $r$ is held between two rigid walls so that it is not allowed to expand. If its temperature is increased, then the force developed in it is proportional to .........

Water falls from a height $500m$. What is the rise in temperature of water at bottom if whole energy remains in the water ........... $^\circ \mathrm{C}$

Give the value of coefficient of volume expansion at $0\,^oC$ for ideal gas.

Surface of the lake is at $2°C$. Find the temperature of the bottom of the lake........ $^oC$

A metallic bar of Young's modulus, $0.5 \times 10^{11} \mathrm{~N} \mathrm{~m}^{-2}$ and coefficient of linear thermal expansion $10^{-5}{ }^{\circ} \mathrm{C}^{-1}$, length $1 \mathrm{~m}$ and area of cross-section $10^{-3} \mathrm{~m}^2$ is heated from $0^{\circ} \mathrm{C}$ to $100^{\circ} \mathrm{C}$ without expansion or bending. The compressive force developed in it is :

On heating a uniform metallic cylinder length increases by $3 \%$. The area of cross-section of its base will increase by ........... $\%$