Question:
A liquid-nitrogen container is made of a $1 \mathrm{~cm}$ thick thermocoal sheet having thermal conductivity $0.025$ $\mathrm{J} / \mathrm{m}-\mathrm{s}^{\circ} \mathrm{C}$ Liquid nitrogen at $80 \mathrm{~K}$ is kept in it. A total area of $0.80 \mathrm{~m}^{2}$ is in contact with the liquid nitrogen. The atmospheric temperature is $300 \mathrm{~K}$. Calculate the rate of heat flow from the atmosphere to the liquid nitrogen.
Solution:
