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accountkiller
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Homework Statement
Note: I know the wording of this post may be lengthy but the problem shouldn't take too long in theory and it's a basic problem from an introductory thermodynamics class so I desperately wish to understand this beginning part so I don't fall behind, so I'd REALLY appreciate any guidance. Thank you!
https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0BwVa69357vahZGExMTU2NWItZTIyMi00NWU4LTg2N2UtODhhOTcwNDhmZjA4&hl=en_US
Homework Equations
[itex]\Delta[/itex]E = Q + W
PV = nRT
The Attempt at a Solution
I'll put up what my study group has worked through and if anyone can tell me if that's the right way to do it or if there is a simpler way, please do so!
D to X : Because it's isothermal, TD = TX, and because in an ideal gas, energy only depends on temperature, [itex]\Delta[/itex]EDX = 0, thus QDX = -WDX
C to X : Because adiabatic means no heat transfer, [itex]\Delta[/itex]ECX = W
B to X: No change in volume, so no work, so [itex]\Delta[/itex]EBX = Q
Now, we were wondering - why is it important to know that A - B is an adiabatic process? So we took it to be a cycle.. X to A to B back to X, and overall [itex]\Delta[/itex]E = 0. So..
[itex]\Delta[/itex]E = -EXA + EAB + EBX = 0.
EXA = EAB + EBX
QXA + WXA = WAB + QBX
QXA = WAB + QBX - WXA
Since QXA equals all of that, QXA > QBX.
Then... the more work you do, the more you heat you need to do the work. Comparing DX to BX, BX has no work and DX does have an "area under the curve" (i.e. work) so QDX > QBX
Then... we took another loop, from X to D to B to A back to X, so that net energy is 0 as well, so:
WAX + QAX + WXD - QXD + WDB + QDB + WAB = 0
If we move QXD to the right side, it is just equal to everything above on left side. Because it is equal to all of that, it must mean that QXD > QAX (since QAX is on the left side).Thus... QDX > QXA > QXB > QXC
Does that look correct? We couldn't find any similar examples online or in our textbooks and this is the first kind of this problem we've run into. We'd appreciate any guidance please :)
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