Two 800\; cm^3 containers hold identical amounts of a monatomic gas at 20^\circ C. Container A is rigid. Container B has a 100\; cm^2 piston with a mass of 10 kg that can slide up and down vertically without friction. Both containers are placed on identical heaters and heated for equal amounts of time. What are the initial pressures in containers A and B? I assumed that the net force was zero and used the equation pressureB = [(weight of piston)/(area of piston)]+101,300 and I assumed that the pressure of the first piston was 101,300 Pa but this was wrong, I'm not sure what else to do??