The vertical surface of a reservoir dam that is in contact with the water is 200 m wide and 10 m high. The air pressure is one atmosphere. Find the magnitude of the total force acting on this surface in a completely filled reservoir.
water is about 1000 kg/m^3
so Pressure= 1 atm + rho g h - 1 atm on empty side
= 1000*9.81*h
average h = 5 meters
so force= 1000 * 9.81 * 5 meters * (200*10)
If they mean only on the wet side then add 1 atm * 200*10