When do formulas for adiabatic processes apply?

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SUMMARY

The discussion centers on the application of formulas for adiabatic processes, specifically the use of the equation PV^γ = constant. It is established that this formula cannot be applied to a system with varying initial pressures or where heat flow occurs between partitions. Instead, the correct approach involves equating pdV with the change in internal energy, which is valid under the condition of an adiabatic process where Q = 0.

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phantomvommand
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Homework Statement
Please see the attached photo
Relevant Equations
Change in internal energy = nCvT
Screenshot 2021-03-14 at 4.29.36 PM.png


In this problem, the method used to solve the question is to equate pdV with change in internal energy. This implies an adiabatic process as Q = 0? (not sure about this claim) However, why is it not correct to simply apply the PV^ϒ = constant formula?

Thank you.
 
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phantomvommand said:
why is it not correct to simply apply the PV^ϒ = constant formula?
What would you apply that to? You cannot apply it to the system as a whole since there are two initial pressures. You cannot apply it to one partition since there is heat flow between them.
 
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