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Math Help - Arc length

  1. #1
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    Arc length

    A cable hangs between two poles of equal height and feet apart.
    At a point on the ground directly under the cable and
    feet from the point on the ground halfway between the poles
    the height of the cable in feet is
    The cable weighs 17.3 pounds per linear foot.
    Find the weight of the cable.
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  2. #2
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    Arc length is:

    L=\int_0^a \sqrt{1+(f'(x))^2} dx

    right? And f(x)=10+0.4x^{3/2}

    So total cable length is 2\int_0^{18}\sqrt{1+(.4(1.5 x^{1/2})^2}dx
    Last edited by shawsend; October 9th 2008 at 02:22 AM. Reason: Corrected formula for f(x)
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  3. #3
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    k i just wasnt sure about the limits. why is it 0 to 18
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  4. #4
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    Quote Originally Posted by amiv4 View Post
    k i just wasnt sure about the limits. why is it 0 to 18
    Because f(x) measures the distance to the cable starting from the lowest point (call that the origin) and the two poles are 36 feet away.
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