If the length of a cylinder on heating increases by $2\%$,the area of its base will increase by ....... $\%$

$A$ metal metre scale that is accurate up to $0.5 \ mm$ is made at a temperature of $25^{\circ} C$. The range of temperatures within which it can be used is (Coefficient of linear expansion of the metal $= 10^{-5} /{ }^{\circ} C$)

$A$ solid rectangular sheet has two different coefficients of linear expansion $\alpha_{1}$ and $\alpha_{2}$ along its length and breadth respectively. The coefficient of surface expansion is (for $\alpha_{1} \Delta t \ll 1, \alpha_{2} \Delta t \ll 1$):

The volume of a metal sphere increases by $0.24\%$ when its temperature is raised by $40^{\circ}C$. The coefficient of linear expansion of the metal is .......... $^{\circ}C^{-1}$.

An iron bar of length $10\, m$ is heated from $0^{\circ}C$ to $100^{\circ}C$. If the coefficient of linear thermal expansion of iron is $10 \times 10^{-6} {^{\circ}C^{-1}}$,the increase in the length of the bar is .......... $cm$.

$A$ cylindrical metal rod of length $L_0$ is shaped into a ring with a small gap $x$ as shown. On heating the system: