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Homework Statement
For point A in the figure (See Figure 1), the pressure is 3 atm, the volume is .08 m3 and the internal energy is 750 J. At point C the values are 1.2 atm, .03 m3, and 420 Joules.
(a) For the cyclic process abcda, how much heat is exchanged with the environment?
(b) For the process abc, what is the change in internal energy?
Homework Equations
delta U = Q  W
where U = internal energy, Q = heat, and W = work
The Attempt at a Solution
for (a), I found Q = 9119.25 J because it's a cyclic process, so delta U = 0 and W_{net} = the area of the square. But for (b), it's not exactly clear how I'm supposed to find the change in internal energy. I can find W by finding the area under the curve, which equals 15198.75 J, but I don't know U now and I don't know Q either. All I can get is Q_{da} > 0, which isn't particularly helpful.
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