# Pressure exerted by a piston

1. Dec 17, 2008

### jonnejon

1. The problem statement, all variables and given/known data
A cylinder with a 16-cm-diameter piston contains gas at a pressure of 3.0 atm.

A.How much force does the gas exert on the piston?

B.How much force does the environment exert on the piston?

C.The gas expands at constant pressure and pushes the piston out 10 cm. How much work is done by the environment?

D.How much work is done by the gas?

2. Relevant equations
P=F/A=N/m^2
W=Fd

3. The attempt at a solution
A. F=(.08^2)(pi)(3)(1.013e5)=6110 N [Correct]
B. F=(.08^2)(pi)(1)(1.013e5)=2040 N[Incorrect]
C. [Unable to calculate due to part B]
D. W=(6110)(.1)=611 J[Correct]

Isn't 1 atm the pressure of the enviroment? Any help would be appreciated.

2. Dec 17, 2008

### alicemunro

im pretty sure you have to convert atms to Pa. 1 x 10^5 Pa = 1atm

3. Dec 17, 2008

### jonnejon

I did convert it into Pa 1 atm = 1.013e5

F = (1.013e5 Pa)(.08 m)^2(pi)= 2037 N, I submitted this but it says incorrect.

4. Dec 17, 2008

### jonnejon

I can't seem to get this right, am I doing something wrong? Please help, its getting frustrating.

5. Dec 18, 2008

Anyone????