Signs in work equations

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madisondesilva1c
Posts: 91
Joined: Fri Sep 28, 2018 12:16 am

Signs in work equations

Postby madisondesilva1c » Fri Feb 08, 2019 9:17 pm

Why is the work quantity in a isobaric process negative, in physics we have learned that w= +pdeltav... Can someone explain where the confusion comes from? Is this due to the fact we are using pressure external?

Brandon_Tran_2E
Posts: 63
Joined: Fri Sep 28, 2018 12:23 am

Re: Signs in work equations

Postby Brandon_Tran_2E » Fri Feb 08, 2019 10:18 pm

I don't know about physics portion of work but Lavelle said the negative sign is because its related to the work of the gas. For example imagine a gas system with a piston, and when the gas expands, delta V would be positive and therefore the work is negative meaning the gas DID work. When the delta V is negative, the work would be a positive value which means work was done on the system to push the gas and decrease the volume. Hope this helps zzz

Xingzheng Sun 2K
Posts: 62
Joined: Fri Sep 28, 2018 12:29 am

Re: Signs in work equations

Postby Xingzheng Sun 2K » Thu Feb 21, 2019 3:57 am

I think the sign of work always depends on if the system does the work or work is done to the system. Once it is determined, the sign of work is figured out.


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