Submarines control their buoyancy using ballast tanks. To sink the tanks can be flooded with water and to rise compressed air can be fed into the tanks to expel the water, lowering the density of the sub. One submarine starts with a neutral buoyancy (i.e. the buoyancy force equals the weight of the submarine) 100m below the surface when it displaces 6.4m^3 of water from its ballast tanks. If the mass of the submarine is 65 metric tons what is the initial, vertical acceleration of the submarine immediately after displacing the water?
[?(water)=1,000 kgm^-3, 1 atm=10^5 N/m^2, g=9.8ms^-2]
What would happen the acceleration if instead of an earth ocean this was a robot submarine on Europa (a moon of Jupiter) where the gravity is roughly one seventh that of earth?