The gate OAB under water is 5 m-wide and is hinged along O as shown.
(a) Find the hydrostatic force on the horizontal surface AB.
(b) Determine the magnitude and point of action of the hydrostatic resultant force on the vertical surface OA.
(c) Draw a free body diagram of the gate and find the horizontal force at point A required to support the gate from opening. Neglect the weight of the gate.