# Weight of a piston

1. Apr 29, 2009

### james brug

1. The problem statement, all variables and given/known data

A vertical cylindrical tank contains 1.80 mol of an ideal gas under a pressure of 1.05 atm at 22.0$$^\circ$$ C. The round part of the tank has a radius of 10.0 cm , and the gas is supporting a piston that can move up and down in the cylinder without friction.

What is the mass of this piston?

2. Relevant equations

pV=nRT

3. The attempt at a solution

$$.05*1 \; atm*.01\pi \: m^2/9.8 \approx 16.2 kg$$

2. Apr 29, 2009

### Andrew Mason

What determines the pressure of the gas in the cylinder? How much of that force (per unit area) is due to the weight of the pistion?

AM