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A gas consisting of two atoms have gamma = 7/5. It is used as "worksubstance" for the following steps:

I: Isobar expansion from V_{1}= 1.00m^{3}to V_{2}= 2.00m^{3}with P_{1}= 3.00*10^{5}Pa

II: adiabatic expansion to (P_{3}, V_{3}), and

III: compression back to (P_{1},V_{1}), as a parabola with bottompoint where (P_{min}= 1.00*10^{5}Pa, and V= V_{2}= 2.00m^{3})

First of all: draw the "circuit" in a PV-diagram. (I use circuit in lack of a better word, suggestions?) :) This goes okey, and then: Find an equation for the "adiabatic" in step II, and for the parabola in step III. Then find the volume V_{3}and the pressure P_{3}.

I cant get past this point.. Excuse my poor english, as this assignment is given in a different language and I therefore had to translate it :) Shout if there are things you dont understand.

2. Relevant equations:

For isobar process: W = p(V2 - V1) and for abdiatic processes: P_{1}*V_{1}^{gamma}= P_{2}*V_{2}^{gamma}, is this all I really need?

3. The attempt at a solution:

My attempt is really poor really. Ive painted a quick scetch of the diagram, and it is attached to the thread. My guesses is that the work W < 0 in II and III, and W > 0 in I?

I really dont know how to find the equations for the abdiatic, or the parabola. My guesses is that I should end up with two equations with V_{3}and P_{3}as unknowns, and solve.

It would be really helpful if you could at least point me in the right direction! :)

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# PV diagram and circuit process!

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