An insulated box containing a diatomic gas of molar mass M is moving with a velocity v. The box is suddenly stopped. The resulting change in temperature is (R is the gas constant)

Let n be the number of moles of the gas in the box. The kinetic energy of the gas = n$\left(\frac{1}{2}M{v}^2\right)$. When the box is suddenly stopped, this energy is used up in changing the internal energy, as a result of which the temperature of the gas rises. The change in internal energy is given by 

                         $∆U=n{C}_v∆T$

For a diatomic gas          $C_v=\frac{5}{2}R.$

Hence            $n\times \frac{5R}{2}\times ∆T=n\times \frac{1}{2}M{v}^2$

or          $∆T=\frac{M{v}^2}{5R}$