4. Adam will be placed across a river with a depth, H, of 13 m, and a width, b, of 45 m. The engineering team selects a concrete structure featuring a curved surface with a constant radius, R, of 10 m, as shown below: The curved surface is tangent to the bottom of the river. Find the hydrostatic force, F (in N), acting on the dam. You should determine both its magnitude and direction