# Thermodynamics Problem

1. Sep 30, 2010

### temaire

1. The problem statement, all variables and given/known data
[PLAIN]http://img821.imageshack.us/img821/8541/cheme.png [Broken]

I am only looking for help in part a.

2. Relevant equations

PV = mRT

3. The attempt at a solution

By looking at the figure, I was able to calculate the volume of state 2, which is half of the volume of state 1.

V1 = (mRT1)/P1
V1 = (5*0.287*573)/200
V1 = 4.11 meters cubed

V2 = V1/2
V2 = 2.06 meters cubed

However, in order to calculate the temperature by using the Ideal Gas Law, I need pressure first. How do I go about finding pressure? Is there an assumption I'm supposed to make first?

Last edited by a moderator: May 5, 2017
2. Sep 30, 2010

### Mapes

How does the pressure arise initially? Can you connect a property of the piston to the pressure?

3. Sep 30, 2010

### temaire

Well, I guess that since the piston does not exert a force on the air, the pressure stays the same throughout state 1 and 2?

Edit: Actually, the pressure arises from the weight of the piston and the atmospheric pressure. So since those two factors stay the same, the pressure is constant throughout states 1 and 2?

Last edited: Sep 30, 2010
4. Sep 30, 2010

### Mapes

The piston doesn't exert a force on the air? Or the piston exerts a constant force regardless of its height?

5. Sep 30, 2010

### temaire

Yeah I edited my post, because I realized that since the atmospheric pressure and the weight of the piston are constant, the pressure doesn't change from state 1 to state 2. Thanks for the help.