For the great depths that may be encountered in the ocean the compressibility of seawater may become an important consideration. (a) assume that the bulk modulus for seawater is constant and derive a relationship between pressure and depth which takes into account the change in fluid density with depth. (b) make use of part (a) to determine the pressure at a depth of 6 km assuming seawater has a bulk modulus of 2.3 x 10^9 pa and a density of 1030 kg/m^3 at the surface. compare this result with that obtained by assuming a constant density of 1030 kg/m^3.