# Homework Help: Help on work done by gas and heat flow

1. Feb 6, 2008

### ZephyR1

1. The problem statement, all variables and given/known data
Heat is allowed to flow out of an ideal gas at constant volume so that its pressure drops from PA = 2.9 atm to 1.4 atm. Then the gas expands at constant pressure, from a volume of 6.8 L to VC = 14.1 L where the temperature reaches its original value. See Fig. 15-27
http://www.webassign.net/giancoli5/15_27alt.gif
(a) Calculate the total work done by the gas in the process.
(b) Calculate the change in internal energy of the gas in the process.
(c) Calculate the total heat flow into or out of the gas. (Heat flow into the gas is positive.)

2. Relevant equations
W=PΔV
ΔU=Q-W

3. The attempt at a solution
(a)W=PΔV
W=1.4*10^5((14.1*10^-3)-(6.8*10^-3))
W=1022J
(b)ΔU=0J since Temp does not change
(c)ΔU=Q-W
0=Q-W
Q=W

I can't get a for some reason and I converted all the units. I know the answer for c is the same as a, but i can't find a. Thanks in advance

Last edited: Feb 6, 2008