An insulated horizontal cylindrical vessel of cross-sectional area A=.12m^2 contains 20 mol of He gas at T0=300K and P0=3 bar in a compartment confined by a moveable piston connected to a spring. The spring constant is k=20 kN/m and the spring is not initially under tension or compression. The right side of the vessel is open to the atmosphere (Patm=1bar,Tatm=300K). At the start of the experiment, the stopper is removed and the gas expands, compressing the spring. Obtain the pressure and temperature of the gas a short time after the stopper has been removed, when a negligible amount of heat transfer has taken place.