Let V be the water velocity in a river of width w and depth d, flowing along at a height h above a hydraulic power station. Show that the maximum electrical power that could be obtained by converting the potential energy of the river water to electrical energy is ρ · V · w · d · h · g, where ρ is the water mass density. Calculate the maximum available power (MW) for w = 20 m, d = 10 m, h = 100 m, V = 2 m/s, using ρ = 1000 kg/m³.