## Volume of the Universe

Volume: $\Delta S = nR\ln \frac{V_{2}}{V_{1}}$
Temperature: $\Delta S = nC\ln \frac{T_{2}}{T_{1}}$

Helen Struble 2F
Posts: 97
Joined: Sat Aug 24, 2019 12:17 am

### Volume of the Universe

So, for calculating entropy of a system vs. the surroundings vs. the total entropy, should we just assume that the entropy of the surroundings is only affected by heat? Is this based on the assumption that any volume change due to piston expanding or contracting is negligible compared to the volume of the universe?

Juliet Stephenson 4E
Posts: 100
Joined: Wed Sep 18, 2019 12:21 am

### Re: Volume of the Universe

Yes, I would say this is a correct assumption.

Anokhi Patel 2B
Posts: 76
Joined: Fri Aug 09, 2019 12:17 am

### Re: Volume of the Universe

Yes, the temperature of the universe does not change, so the change in entropy is the negative heat of the system minus heat of the surroundings.

SimranSangha4I
Posts: 99
Joined: Sat Sep 14, 2019 12:17 am

### Re: Volume of the Universe

Yes! That sounds right since the heat of the universe doesn't change.

William Francis 2E
Posts: 101
Joined: Wed Sep 18, 2019 12:20 am

### Re: Volume of the Universe

Yes. The universe is pretty large compared to the piston, so the volume change is pretty negligible.