A vacuum system consists of a chamber of volume V connected to a vacuum pump that is a cylinder with a piston that moves left and right. The minimum volume in the pump cylinder is V0, and the maximum volume in the cylinder is V0+ΔV. You should assume that ΔV≪V.
[Figure: Diagram showing chamber connected to cylinder with piston, motor, inlet and outlet valves]
The cylinder has two valves. The inlet valve opens when the pressure inside the cylinder is lower than the pressure in the chamber, but closes when the piston moves to the right. The outlet valve opens when the pressure inside the cylinder is greater than atmospheric pressure Pa, and closes when the piston moves to the left. A motor drives the piston to move back and forth. The piston moves at such a rate that heat is not conducted in or out of the gas contained in the cylinder during the pumping cycle. One complete cycle takes a time Δt. You should assume that Δt is a very small quantity, but ΔV/Δt=R is finite. The gas in the chamber is ideal monatomic and remains at a fixed temperature of Ta.
Start with assumption that V0=0 and there are no leaks in the system.
a. At t=0 the pressure inside the chamber is Pa. Find an equation for the pressure at a later time t.
b. Find an expression for the temperature of the gas as it is emitted from the pump cylinder into the atmosphere. Your answer may depend on time.
For the remainder of this problem 0<V0<ΔV≪V.
c. Find an expression for the minimum possible pressure in the chamber, Pmin.