I am trying the solve the following diff. eq. with NDSolve in mathematica:(adsbygoogle = window.adsbygoogle || []).push({});

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

and

[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.

Thanks

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# Solving a projectile problem with mathematica

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