In Example 4, find the force on the floodgate if the upper edge is 2.00 ft below the surface.
EXAMPLE 4 Force on floodgate
A vertical rectangular floodgate of a dam is 5.00 ft wide and 4.00 ft high. Find the force on the floodgate if its upper edge is 3.00 ft below the surface of the water. See Fig. 26.67. Each element of area of the floodgate has a length of 5.00 ft, which means that l = 5.00 ft Because the top of the gate is 3.0 ft below the surface a = 3.00 ft and since the gate is 4.00 ft high b = 7.00 ft 
e have the force
on the gate as
