Consider a reservoir filled with water of uniform density po and subject to the gravi- tational force. One side of the reservoir is confined by a dam wall of height h and width W, as shown in the picture below. The surface of the reservoir is located at z = 0, where the pressure is P(z = 0) = Po. air 0 dz t W water -h (a) Assuming that the water in the reservoir is at equilibrium, derive a solution for the pressure as a function of height, P(z) (justify your answer). [3 Marks] (b) Find the pressure force exerted by the water on a horizontal strip of the dam, at height 2, with infinitesimally small vertical thickness dz. [4 Marks]