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Homework Help: Find the equations of the trajectories?

  1. Feb 12, 2015 #1
    1. The problem statement, all variables and given/known data
    Find the equations of the trajectories of y"+y^3=0.

    2. Relevant equations

    3. The attempt at a solution
    The Undamped Case:
    So following the formula above:
    The answer I got is v^2/2+y^4/4=C, but the answer in the book says v^2+y^4/4=C. What's wrong?
  2. jcsd
  3. Feb 12, 2015 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    Did you, blindly, followed a formula?

    What makes you think the formula applies in this case?
    Did you follow the formula correctly?
    Did you check your algebra?
    Did you check your arithmetic?

    Maybe the book made a typo?
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