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Topic: Misner, Thorne and Wheeler, Exercise 8.5 (c)
Replies: 38   Last Post: Apr 13, 2013 11:57 PM

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 Dono Posts: 368 Registered: 11/6/06
Re: Misner, Thorne and Wheeler, Exercise 8.5 (c)
Posted: Apr 13, 2013 7:12 PM

On Apr 8, 6:08 pm, rotchm <rot...@gmail.com> wrote:
>
> Yes, thats a "trivial" solution  and as you hinted, there are others.
> The general solution to this is
> r = s(At2 + Bt  + C), which can be ~ at + b if its a perfect square.
>

You mean r=\sqrt(At^2+Bt+C), arithmetic ignoramus.

r = s(At2 + Bt + C) is nothing but a polynomial degree 2 multiplied
by "s", whatever that may be. And, as such, this isn't a solution for
the ODE.

You can't even write the solution correctly. I hate to break it to you
but even as you copied this solution from a free software package, it
isn't the correct solution. You were too lazy in your copying, A, B
and C aren't arbitrary, they are tied to each other through some
constants of integration, c1=r(0), c2=r'(0) and c3=r"(0), as the final
solution needs to depend on the initial conditions. But you are too
big of an idiot to know this.