## Heat transfer

$\Delta U=q+w$

Isabella Sanzi 2E
Posts: 54
Joined: Thu Jul 13, 2017 3:00 am

### Heat transfer

On the last test, one of the questions was discussing whether or not heat was being transferred when a balloon filled with gas was expanded to a larger volume and lower pressure while maintaining the same temperature. I thought that it was not because the temperature was not changing, however the answer is yes, so I was just wondering why that is. Thanks!

Jana Sun 1I
Posts: 52
Joined: Sat Jul 22, 2017 3:00 am

### Re: Heat transfer

I think this person had the same question: viewtopic.php?f=130&t=26744.

I don't think I got the same question on the test, but for the situation you're describing, work would be done at least (because there's a change in volume and pressure).

Cassandra Mullen 1E
Posts: 54
Joined: Fri Sep 29, 2017 7:07 am
Been upvoted: 2 times

### Re: Heat transfer

This is an example of an isothermal process (no heat change) where the energy lost by the system is supplemented by the energy gained in the surroundings.

Bansi Amin 1D
Posts: 51
Joined: Fri Sep 29, 2017 7:05 am
Been upvoted: 1 time

### Re: Heat transfer

Heat was being transferred to make up for the energy change.

Ozhen Atoyan 1F
Posts: 50
Joined: Thu Jul 27, 2017 3:01 am
Been upvoted: 1 time

### Re: Heat transfer

I had this question on my test. My answer was that heat is being transferred, because the volume and pressure are changing. This means the energy is being altered.

Wenjie Dong 2E
Posts: 53
Joined: Fri Jun 23, 2017 11:40 am

### Re: Heat transfer

Same question!

Sarah 2F
Posts: 33
Joined: Fri Sep 29, 2017 7:06 am

### Re: Heat transfer

Heat is being transferred because pressure and volume are changing. Even though the temperature is constant, that is because the changing temperature evens out and becomes non changing even though its gaining some and losing some from the pressure and volume change.

Abby Ellstrom 1I
Posts: 53
Joined: Fri Sep 29, 2017 7:04 am

### Re: Heat transfer

There is work being done because W=PdeltaV and there is a change in volume therefore there must be a change in work as long as its not free expansion.