## Change in internal energy

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

Ryan Danis 1J
Posts: 66
Joined: Fri Sep 28, 2018 12:18 am

### Change in internal energy

How do I calculate the change in internal energy of a system if the amount of heat transferred is not given? (7th edition 4A.3 part c)

Aria Soeprono 2F
Posts: 64
Joined: Fri Sep 28, 2018 12:27 am

### Re: Change in internal energy

The internal energy of a system does not necessarily mean heat, it can also be referring to work, because U= heat + work. Therefore, in 4A. 3 (c), delta U is equal to the amount of work done, which is 28 J.

Ryan Danis 1J
Posts: 66
Joined: Fri Sep 28, 2018 12:18 am

### Re: Change in internal energy

So the answer is 28J! The back of the book said the answer was 8J so it must be a typo, no wonder I was so confused. Thanks for your explanation!

Mya Majewski 1L
Posts: 89
Joined: Fri Sep 25, 2015 3:00 am

### Re: Change in internal energy

Have we even went over internal energy in class yet (Delta U)?