The Attempt at a Solution
How to do part biii?
I tried to find change of U and W, then use ΔU-W=Q=0.
I can find the change in U by using the fact the rms of the x-component of the velocity is doubled. Therefore, originally, if isotropic <c2> = <vx2>+<vy2>+<vz2> = 3<v2x>,
now the new <vx2> is 4 times the old one, so the new mean square <c'2>=6<vx2>=2<c2>, so the new internal energy is double the old one. How about the work done? How to find it? I have only learnt how to find adiabatic, isothermal and constant volume work done.