# Math Help - hydrostatic force

1. ## hydrostatic force

Can anyone help me with this word problem ? -__-

1.
A dam is inclined at an angle of 30± from the vertical and has the shape of an isoceles trapezoid 100 ft wide at the top and 50 ft wide at the bottom and with a slant height of 70 ft. Find the hydrostatic force on the dam when it is full of water.

Thanks!

2. nevermind i got the answer yay!!

3. Whoa I got this same problem.. How do you do it?

4. Since it is 30 degrees to the vertical, then we can use sin(60), which I will represent in radians.

$62.4\int_{0}^{70}(xsin(\frac{\pi}{3}))(100)dx$

I think mostly I'm having trouble drawing the picture, so I can't really get any farther than that. Would you mind redrawing with the given information?

Thanks!

6. christinaaa, r u also in pham's class ? lol

for finding height of dam = sqrt((70)^2 - (25)^2) cos30

then for width of trapezoid = 100-x/h (100-50)

then u take the integral of the width which u got from above, from 0 to h

7. Do you have a picture?

Isn't the formula for hydrostatic force something like F = the integral of 1000 x 9.8 x area of the dam, from 0 to h?