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Solve second order nonlinear differential equation

  1. Sep 7, 2015 #1
    how do you solve this equation?

    y´´ + k/(y^2) = 0 ? I got it from applying Newton's 2nd law of motion to an object falling from space to earth only affected by gravitational force. Thank you!
     
  2. jcsd
  3. Sep 7, 2015 #2

    vanhees71

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    Is this a homework problem? If so, you should post it in the homework section. So I'll give only a hint to the solution:

    You can find a first integral of the equation of motion, which is nothing than energy conservation, by multiplying with ##\dot{y}## (assuming that your prime means in fact a time derivative). Then you get a first-order equation, which can be solved by separation of variables.
     
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