## 8.13

$w=-P\Delta V$
and
$w=-\int_{V_{1}}^{V_{2}}PdV=-nRTln\frac{V_{2}}{V_{1}}$

Samira 2B
Posts: 38
Joined: Fri Sep 29, 2017 7:05 am

### 8.13

For this problem, why is the heat added (947 kJ) negative? I thought when you add heat to a system it is supposed to be positive?

Nishma Chakraborty 1J
Posts: 51
Joined: Fri Sep 29, 2017 7:04 am

### Re: 8.13

Hey!

So, I think it's -947 kJ because the cylinder itself isn't absorbing the heat (then it would be +947 kJ), but rather the cooling system around it is absorbing the heat. Basically, the cylinder is giving off the heat (thus -947 kJ) that the cooling system absorbs. The wording is tricky!

Hope this helps! :)

204918982
Posts: 50
Joined: Fri Sep 29, 2017 7:04 am

### Re: 8.13

The cylinder itself is losing energy so the heat is negative