Solving Kepler's 2nd Law: Determine a & e from E, l, m, M, and G

[Physics Help!]

A satellite of mass m is in Keplerian orbit around a parent body of mass M >>m. The satellite has total energy E and angular momentum l, where angular momentum is measured about the parent body and the zero of potential energy is at infinity. Determine the semimajor axis a and the eccentricity e of the orbit, in therms of the above quantities and Newton'ss constant G (use the symbol, not the numerical value). HINT: Find the relation among the energy, angular momentum and orbit raduis at the apside of the orbit. Solve this relation for the apsidal radii r*, and use the fact that the apsidal radii are r*= a(1+-e).

 

[gneill]

what have you tried so far? You should provide some attempt at attacking the problem, or at least your thoughts on how to do so, otherwise there's not much we can do to help!