1st law of thermodynamics, work/heat

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The discussion focuses on applying the first law of thermodynamics to a problem involving adiabatic expansion and ideal gases. The key equations mentioned include the relationship between work, internal energy, and temperature changes, as well as the ideal gas law. The user is attempting to calculate work done during the expansion but is stuck on determining the temperatures at different states. Suggestions include using the ideal gas law to find these temperatures before proceeding with the calculations. The conversation emphasizes the importance of understanding the thermodynamic principles involved in the problem.
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Homework Statement


http://img404.imageshack.us/img404/1913/captureop6.jpg

Homework Equations


adiabatic expansion: q = 0
deltaU = w = Cv (T2-T1)
reversible (ideal gas): P1V1 = P2V2
gamma = Cp/Cv
Cp - Cv = R

The Attempt at a Solution


V1 = nRT/P1
V2 = nRT/P2
Combine into w = -P2 (V2 - V1)

This is where I got stuck.
 
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Use the ideal gas law equation to find the temperatures first. Did you do this? What are the temperatures at states 1,2, and 3?
 
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