D. C. Pandey Solutions for Chapter: Calorimetry and Heat Transfer, Exercise 2: INTRODUCTORY EXERCISE 22.2

Find SI units of thermal resistance.

Suppose a liquid in a container is heated at the top rather than at the bottom. What is the main process by which the rest of the liquid becomes hot?

Three rods each of the same length and cross-section are joined in series. The thermal conductivity of the materials are $K$, $2K$ and $3K$, respectively. If one end is kept at $200 °\mathrm{C}$ and the other at $100 °\mathrm{C}$. What would be the temperature of the junctions in the steady-state? Assume that no heat is lost due to radiation from the sides of the rods.

A rod $CD$ of thermal resistance $5 \mathrm{K} {\mathrm{W}}^{-1}$ is joined in the middle to an identical rod $AB$ as shown in the figure. The ends $A$, $B$ and $D$ are maintained at $100 °\mathrm{C}$, $0 °\mathrm{C}$ and $25 °\mathrm{C}$, respectively. Find the heat current in $CD$.

A liquid takes $5 \mathrm{minutes}$ to cool from $80 °\mathrm{C}$ to $50 °\mathrm{C}$. How much time will it take to cool from $60 °\mathrm{C}$ to $30 °\mathrm{C}$? The temperature of the surroundings is $20 °\mathrm{C}$.