Question

What will be the new area of 400cm square of a solid if it's temperature is raised by 10kelvin

Answer 1

If the linear expansion coefficient is $\alpha$ , the new area after heating will be

$$A=A_0(1+\alpha T)^2=400(1+10\alpha)^2\text{ cm}^2.$$

For instance, for brass square with $\alpha=19\cdot10^{-6}\text{ K}^{-1}$ the new area will be 400.15 cm²