Two piston/cylinder arrangements, A and B, have their gas chambers connected by a pipe. Cross-sectional areas are AA = 75 cm2 and AB = 25 cm2 with the piston mass in A being mA = 25 kg. Outside pressure is 100 kPa and standard gravitation. Find the mass mB so that none of the pistons have to rest on the bottom.
Force balance for both pistons:
F↑ = F↓
A: mPAg + P0AA = PAA
B: mPBg + P0AB = PAB
Same P in A and B gives no flow between them.
=> mPB = mPA AA/ AB = 25 × 25/75
= 8.33 kg
