Math Help Forum: hydrostatic force

  1. #1
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    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!
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  3. #2
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    nevermind i got the answer yay!!
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  4. #3
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    Whoa I got this same problem.. How do you do it?
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  5. #4
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    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
    Attached Thumbnails Attached Thumbnails hydrostatic force-dam.gif  
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  6. #5
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    Thanks for your help!

    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!
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  7. #6
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    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
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  8. #7
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    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?
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