13 The photograph shows a submarine below the surface of the sea. (a) The submarine has a volume of 5.83 × 10³m². The submarine is stationary in a region of

the sea where the density of the seawater is 1.03 × 10'kgm (i) Calculate the upthrust exerted on the submarine by the seawater. (ii) Explain why the mass of the submarine must be 6.0 × 10¢kg. ) The submarine now moves into a region of the sea where the water is less safety the density of the water reduces to 1.01 × 10³ kgm³. ) Explain what would happen to the submarine as it moves into this region of lower density seawater. (ii) The submarine alters its weight by pumping water in or out of its internal tanks. Determine the mass of water that the submarine should pump, in or out of its-tanks, to maintain its depth below the surface of the sea.