In an adiabatic process, the volume of an ideal gas gets doubled and the mean collision time between the qas molecules changes from ${\tau }_1\text{ to }{\tau }_2$. Then a good estimate for $\frac{{\tau }_2}{{\tau }_1}$ is given by if $\frac{{\mathrm{C}}_{\mathrm{P}}}{{\mathrm{C}}_{\mathrm{y}}}=\gamma$ for this gas