A black body of mass $34.38 \mathrm{~g}$ and surface area $19.2 \mathrm{~cm}^2$ is at an initial temperature of $400 \mathrm{~K}$. It is allowed to cool inside an evacuated enclosure kept at constant temperature $300 \mathrm{~K}$. The rate of cooling is $0.04^{\circ} \mathrm{C}$ per second. The…

Question

A black body of mass $34.38 \mathrm{~g}$ and surface area $19.2 \mathrm{~cm}^2$ is at an initial temperature of $400 \mathrm{~K}$. It is allowed to cool inside an evacuated enclosure kept at constant temperature $300 \mathrm{~K}$. The rate of cooling is $0.04^{\circ} \mathrm{C}$ per second. The specific heat of the body in $\mathrm{J} \mathrm{kg}^{-1} \mathrm{~K}^{-1}$ is (Stefan's constant $\sigma=5.73 	imes 10^{-8} \mathrm{Wm}^{-2} \mathrm{~K}^{-4}$

Aicharya · Accepted Answer

$ \frac{d 	heta}{d t}=\frac{\sigma A\left(T^4-T_0^4ight)}{m s} $ $	herefore$ Specific heat $s=\frac{\sigma A\left(T^4-T_0^4ight)}{m\left(\frac{d 	heta}{d t}ight)}$ Substituting the values $ \begin{aligned} & s=\frac{\left(5.73 	imes 10^{-8}ight)\left(19.2 	imes 10^{-4}ight)\left[(4)^4-(3)^4ight] 	imes 10^8}{\left(34.38 	imes 10^{-3}ight)\left(4 	imes 10^{-2}ight)} \ & 	herefore \quad s=1400 \ & \end{aligned} $

A black body of mass $34.38 \mathrm{~g}$ and surface area $19.2 \mathrm{~cm}^2$ is at an initial temperature…

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