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Physics
Classical Physics
Thermodynamics
Adiabatic expansion work far exceeds isobaric of same volume, why?
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[QUOTE="Chestermiller, post: 6849179, member: 345636"] No. The PV work is always ##\int{P_{ext}dV}##, where ##P_{ext}## Is the absolute external pressure. In the first calculation you did, you considered an adiabatic reversible expansion, starting with an external pressure 0f 10 psi gauge and lowering the external pressure gradually to 0 psi gauge. The equation you used to get to work was specifically for this case. For the adiabatic irreversible isobaric expansion you were considering in the second case, I believe you intended to start out at 10 psi gauge again, but in this case to suddenly drop the external pressure to zero psi gauge and to hold that external pressure constant until the gas had expanded by the same volume as in the first case. So ##\Delta V=44.9\ in^3=0.000736\ m^3## and ##P_{ext}=14.7\ psi=101.325\ kPa##, and the work is W = 74.6 J. [/QUOTE]
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Forums
Physics
Classical Physics
Thermodynamics
Adiabatic expansion work far exceeds isobaric of same volume, why?
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