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  1. #1
    Member CalcGeek31's Avatar
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    Work

    A force of 7 pounds compresses a 15 inch spring a total of 4 inches. How much work is done in compressing the spring another 3 inches?
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  2. #2
    MHF Contributor
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    Quote Originally Posted by CalcGeek31 View Post
    A force of 7 pounds compresses a 15 inch spring a total of 4 inches. How much work is done in compressing the spring another 3 inches?
    use Hooke's law, F = kx , ... find the spring constant k

    W = \int_4^7 kx \, dx
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  3. #3
    MHF Contributor Calculus26's Avatar
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    Set the 0 to be at 15 the natural length of the spring

    F = kx

    7 = 4k

    so k = 7/4

    F = (7/4)x

    W = integral [from -4 to -7 of (7/4)xdx]
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