P2_7 Underwater Hot Air Balloon

Abstract

This paper analyses how a Bathyscaphe vessel, which uses gasoline to provide lift and weights and air tanks to lower the vessel, can travel to the bottom of the Mariana Trench and return to the surface again. When the air tanks are full, the vessel is neutrally buoyant on the surface with a density of ρ_surf = 1022 kg/m^3 . When the air tanks are flooded with water, the vessel becomes negatively buoyant, with the vessel density now equal to ρ_sink ≈ 1100 kg/m^3 , thereby causing the vessel to sink. Once it reaches the bottom, the weights are dropped which causes the vessel to become positively buoyant, with the vessel density now equal to ρ_rise ≈ 1020 kg/m^3.