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Solving a projectile problem with mathematica

  1. Mar 12, 2007 #1
    I am trying the solve the following diff. eq. with NDSolve in mathematica:

    [itex] \ddot{x}(t) = - \frac{GMx(t)}{(x(t)^2+y(t)^2)^{\frac{3}{2}}}[/itex]
    [itex] \ddot{y}(t) = - \frac{GMy(t)}{(x(t)^2+y(t)^2)^{\frac{3}{2}}} [/itex]

    where [itex]GM=3.6018*10^{14}[/itex], the initial conditions are:
    [itex] x(0)=0, y(0)=6000000 [/itex]
    and [itex] vx0, vy0 [/itex] can be whatever.

    The trouble is, I keep an error of some sort. I do not have a huge amount of experience with NDSolve so I am most likely doing something simple wrong. The latest thing I have tried is included as an attachment, and resulted in the error:
    NDSolve::ndnum: Encountered non-numerical value for a derivative at t == 0.`.

    If someone can point out what I'm doing wrong I would be very gratefull. I also have access to Maple if you know how to solve the problem using that, instead of Mathematica.

    Attached Files:

  2. jcsd
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