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11.Thermodynamics
normal
An insulated box containing a diatomic gas of molar mass $m$ is moving with velocity $v$. The box is suddenly stopped. The resulting change in temperature is :-
A
$\frac{mv^2}{2R}$
B
$\frac{mv^2}{3R}$
C
$\frac{mv^2}{5R}$
D
$\frac{2mv^2}{5R}$
Solution
Apply energy conservation
work done $=$ loss in kinetic energy
$\frac{\mu \mathrm{R}}{(\mathrm{Y}-1)}\left(\mathrm{T}_{1}-\mathrm{T}_{2}\right)=\frac{1}{2} \mathrm{mV}^{2}$
$\left(\frac{\mathrm{M}}{\mathrm{m}}\right) \frac{\mathrm{R}\left(\mathrm{T}_{1}-\mathrm{T}_{2}\right)}{\left(\frac{7}{5}-1\right)}=\frac{1}{2} \mathrm{MV}^{2}$
Hence $\mathrm{T}_{1}-\mathrm{T}_{2}=\Delta \mathrm{T}=\frac{\mathrm{mV}^{2}}{5 \mathrm{R}}$
Standard 11
Physics