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Homework Help: Orbit Parameters and Energy

  1. Mar 23, 2010 #1


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    1. The problem statement, all variables and given/known data

    Ok so take r' to be r dot..

    i have E = 1/2m (r' ^2 + h^2/r^2) - A/r = E

    Energy equation for central force (inverse square)

    and r = l/(1+ecostheta) where l is the latus rectum..

    need to derive the expression linking E and e i.e. E= A^2/2mh^2 (e^2-1) but cant seem to get there...

    any help would be great..

    2. Relevant equations

    3. The attempt at a solution

    well for a start, when you differentiate r, the result includes a term theta dot -- where does that go?!
  2. jcsd
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