Thermal Properties of Matter MCQs for NEET — Physics Questions with Answers

The introductory part of the chapter mentions: 'You will also learn what happens when water boils or freezes, and its temperature does not change during these processes even though a great deal of heat is flowing into or out of it.' This refers to the phase change process, where temperature remains constant during melting/freezing.

The text states: '...when the temperature of body... and its surrounding medium are different, heat transfer takes place between the system and the surrounding medium, until the body and the surrounding medium are at the same temperature.'

The Thermodynamics chapter states: 'Historically, it took a long time to arrive at the proper concept of ‘heat’. Before the modern picture, heat was regarded as a fine invisible fluid filling in the pores of a substance. On contact between a hot body and a cold body, the fluid (called caloric) flowed from the colder to the hotter body!'

$F = YA\alpha\Delta T = 0.5\times 10^{11} \cdot 10^{-3} \cdot 10^{-5} \cdot 100 = 5\times 10^4 = 50\times 10^3$ N.

Equal heat current: $2(3T-T_1) = (T_1-T_2) = 2(T_2-T)$. Solving gives $T_1 = \tfrac{5T}{2}$, $T_2 = \tfrac{3T}{2}$, so $\dfrac{T_1}{T_2} = \dfrac{5}{3}$.