Question

A dam is inclined at an angle of 30 rom the vertical and has the shape of an isosceles trapezoid 180 ft wide at the top and 90 ft wide at the bottom and with a slant height of 130 ft. Find the hydrostatic force on the dam when it is full of water. (Round your answer to the nearest whole number. Recall that the weight density of water is 62.5 lb/ft',)

Answer 1

hydrostatic force F = Pressure (p) times Area (A) Given inclined angle = 30 degree, then height = 130 gas 30 degree ft pressure when dam is full, P = h rho g = (130 times squareroot 3/2) times 62.5 times (9.8 times 3.28) density rho = 62.5 lb/ft^3, p = 226179.8 lb/ft middot sec^2 and Area A = {1/2 (180 + 90) times 4 cos 30} = 135 ft^2 times 40 cos 30 degree ft = 4676 ft^2 then Force F = 10.5 times 10^8 ft middot lb/sec^2