Question

A scuba tank, when fully submerged, displaces 15.7 liters of seawater. The tank has a total mass of 14 kg when empty; when full, it contains 3 kg of air. a) If you release the full (from from a spot underneath the surface of the ocean, does it sink, remain at that spot, or rise to the surface? Explain. b) If the tank is initially 2 m below the ocean surface, determine the pressure that the ocean water exerts on it there.

Answer 1

a) Tank weight = 14 * 9.8

                           = 137.2 N

     Air weight = 3 * 9.8

                       = 29.4 N

=> total weight =   137.2 +   29.4

                         = 166.6 N

=>   Buoyant force = 0.0157 * 1025 * 9.8 = 157.706 N

Thus, it will sink .

b)   the pressure that the ocean water exerts on it there =   rho * g * h

                                                                                         = 1025 * 9.8 * 2

                                                                                        = 20090 Pa