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Help with nonlinear differential equation?

From the simple problem of picking up a chain subject to gravity with a constant force, the equation of motion looks like:

(a - bL) = L(L''), where a and b are constants.

Is this solvable for L(t)?

1 Answer

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  • xyzzy
    Lv 7
    6 years ago
    Favorite Answer

    v = dL/dt

    dv/dt = dv/dL dL/dt = dv/dL v = L ''

    (a - bL) = L dv/dL v

    a/L - b dL =v dv

    a ln L - bL + c = 1/2 v^2

    (2 a ln L + 2b L + c)^1/2 = v

    (2 a ln L + 2b L + c)^1/2 = dL /dt

    dt = (2 a ln L + 2b L + c)^-1/2 dL

    and now I am stuck.

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