In a compressed air space there is a suspended mass with 10 cubic meters volume. The pressure vessel is 20 atm. The suspended mass is suspended 100 meters over water that is kept at bay by the air pressure inside the vessel. The moment the mass is released its potential energy converts to kinetic energy. There is a door that closes off the 10 cubic meters of volume space so that there is 20 atm of pressure inside (E=PV). The mass falls and impacts the water and submerges. The water level rises. Does the pressure inside the vessel decrease by 10m3 x 20 atm? Is the PV energy inside the closed space equal to 10m3 x 20 atm minus air resistance? Can this be written in math? Can this idea be expressed mathematically?