A monoatomic gas of mass 4.0 u is kept in an insulated container. Container is moving with velocity 30 m / s. If container is suddenly stopped then…

A monoatomic gas of mass $\displaystyle 4.0$ u is kept in an insulated container. Container is moving with velocity $\displaystyle 30 \mathrm{~m} / \mathrm{s}$. If container is suddenly stopped then change in temperature of the gas $\displaystyle (R=$ gas constant $\displaystyle )$ is $\displaystyle \frac{x}{3 R}$. Value of $\displaystyle x$ is \_\_\_\_.