Reversible Expansions

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Nicole Nikolov 1K
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Joined: Fri Sep 29, 2017 7:05 am

Reversible Expansions

Postby Nicole Nikolov 1K » Thu Mar 15, 2018 4:59 pm

I understand that the work a system can do is greatest in a reversible process. For example, if you look at a PV diagram you can see that the area under a curve is greatest for a reversible process. However, I am having trouble understanding it from more of a mathematical viewpoint. Can someone please explain why this is so in a more quantitative way? Thanks.

704887365
Posts: 49
Joined: Sat Jul 22, 2017 3:00 am

Re: Reversible Expansions

Postby 704887365 » Fri Mar 16, 2018 7:16 pm

I’m not sure how to explain it quantitatively but work done reversibly does not lose as much heat energy (due to friction and other unwanted processes)

Michael Downs 1L
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Joined: Thu Jul 13, 2017 3:00 am

Re: Reversible Expansions

Postby Michael Downs 1L » Fri Mar 16, 2018 10:01 pm

^

melissa carey 1f
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Joined: Fri Sep 29, 2017 7:06 am

Re: Reversible Expansions

Postby melissa carey 1f » Sat Mar 17, 2018 12:03 pm

In a TA review session he explained that when you have a rev process you are extracting the max work bc you are making such small changes that you can appoximate P-internal = P-external at every instant. PV=nRT. P=nRT/v. substitute w=-nRT/V and integrate w respect to V. this is where you get w = -nRTln(Vf/Vi).
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