## delta u sign

Sahand Fardi 1
Posts: 19
Joined: Wed Sep 21, 2016 2:56 pm

### delta u sign

for the delta u equation that states delta u= delta h-p(delta v), does the sign in the middle become plus when there is work being done on the system? Or, is it always minus regardless of work done on or given off?

Azeel_Mohammed_1C
Posts: 10
Joined: Wed Nov 18, 2015 3:00 am

### Re: delta u sign

Yes, from what I know, it does become a positive when work is being done on the system.

Josephine_Tang_1N
Posts: 30
Joined: Wed Sep 21, 2016 2:57 pm

### Re: delta u sign

Right - this is since the volume decreases (negative $\Delta$V) and corresponds to a change from: - P$\Delta$V to + P$\Delta$V.