Solve the foregoing problem, assuming that the discs are located in an ultra-rarefied gas of molar mass `M`, at temperature `T` and under pressure `p`.

Explanation

In the ultrasound gas we must determine `eta` by taking `lamda = (1)/(2)`. Then
`eta = (1)/(3) sqrt((8 kT)/(m pi)) xx (1)/(2) h xx(mp)/(kT) = (1)/(3) sqrt((2 M)/(pi RT)) hp`
so, `N = (1)/(3) omega a^4 p sqrt((pi M)/(2 RT))`.