## Ideal Gas Law- delta U

$\Delta U=q+w$

DanielaWong_2G
Posts: 20
Joined: Wed Sep 21, 2016 2:56 pm

### Ideal Gas Law- delta U

Hi! So I realize that when V is constant, w=0 (although I'm not sure why), but why is delta U =0 when delta T is 0? Is it derived from equations or is just something we're supposed to know?

Cherry_Deng_1K
Posts: 12
Joined: Wed Sep 21, 2016 2:55 pm

### Re: Ideal Gas Law- delta U

Hey there! First of all, w=0 when there is no volume change because it means that the system is not doing any work (imagine a system where work causes a piston to move up and down. If the volume of the system doesn't change, then the piston isn't moving, so no work is being done). For your question about delta T, internal energy change depends on the temperature. If delta T=0 (meaning temperature is constant), then internal energy will also be constant. Therefore delta U = 0. Hope this helps!