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w=-P*deltaV

Posted: Sat Jan 20, 2018 11:57 pm
by Janice Xiao 1I
Can someone explain why there's a negative sign in the w=-P*deltaV equation?

Re: w=-P*deltaV

Posted: Sun Jan 21, 2018 12:08 am
by Jason Liu 1C
At a constant pressure, if volume increases, it means that the system is expanding and energy is leaving the system as work. This leaves the system with a lower internal energy. The negative sign means that when a system expand, it is losing energy as work.

Re: w=-P*deltaV

Posted: Sun Jan 21, 2018 5:05 pm
by Julianna Thrasher 1B
We use this equation when the system is at equilibrium (and is therefore reversible) in order to calculate work done by expansion against constant pressure and slight changes in volume. The negative sign shows the system is losing energy.

Re: w=-P*deltaV

Posted: Sun Jan 21, 2018 5:14 pm
by aTirumalai-1I
Take a look at this response; it really helped me understand the conceptual reasoning behind it:

viewtopic.php?t=2341