# Homework Help: Thermodynamic Problem

1. Feb 25, 2010

### alex1261

2. Feb 25, 2010

### rock.freak667

At state 2, when the mass is in equilibrium, you need to do a force balance. Remember F=PA. Then look at the temperatures of states 1 and 2. What type of process is that?

3. Feb 26, 2010

### alex1261

Thanks ! i have managed to solve a and b but now i am stuck on c I believe the answer to c is isobaric, because P=F/A is not affected by the growing volume nor the temperature. and it can't be isothermal because the temperature is changing. and I don't quite understand how adiabatic works.

4. Feb 26, 2010

### alex1261

Ok my answer to the volume are wrong, do I use P1V1=P2V2 or do I use PV=nRT equation ?

5. Feb 28, 2010

### alex1261

can anyone help please ? I've figured out pressure, but i'm stuck on how to find volume

6. Feb 28, 2010

### rock.freak667

I think you should use P1V1=P2V2, that is supposed to work when T=constant.

7. Feb 28, 2010

### alex1261

yeah I was considering that. And to find the volume in state 4, I would have to use PV=nRT correct ? since T isn't constant ?

8. Feb 28, 2010

### rock.freak667

From state 3 to 4, it looks like T=100°C for both 3 and 4. So while you can use PV=nRt at 4, you should be able to use P3V3=P4V4 as well