How does one derive the total energy in an elliptic orbit:(adsbygoogle = window.adsbygoogle || []).push({});

[tex]E= - \frac{GMm}{2a}[/tex]

where a is the semi-major axis?

I did manage to get the result for the special case of circular orbit, as

[tex]v = \sqrt{\frac{GM}{R}}[/tex]

But the problem is that I can't figure out a way to express v in an elliptic orbit.

If at all possible, give hints (that is: not a direct answer), as I'd rather try it myself first :).

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# Homework Help: Energy in elliptic orbits

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