JEE PHYSICS MCQ: THERMAL PROPERTIES OF MATTER

A metal rod of cross sectional area $1.0 \mathrm{~cm}^2$ is being heated at one end. At one time, the temperature gradient is $5.0^{\circ} \mathrm{C} \mathrm{cm}^{-1}$ at cross section $A$ and is $2.5^{\circ} \mathrm{Ccm}^{-1}$ at cross section $B$. Calculate the rate at which the temperature is increasing in the part $A B$ of the rod. The heat capacity of the part $A B=0.40 \mathrm{~J}^{\circ} \mathrm{C}^{-1}$, thermal conductivity of the material of the $\operatorname{rod}=200 \mathrm{~W} \mathrm{~m}^{-1}{}^\circ \mathrm{C}^{-1}$. Neglect any loss of heat to the atmosphere.