1. The problem statement, all variables and given/known data It is required to put a satellite into an orbit with apogee of 5R/2, where R is the radius of the planet. The satellite is to be launched from the surface with a speed Vo at 30degrees to the local vertical. If M is the mass of the planet, show that (Vo)^2 = 5GM/4R. Assume zero rotation. 2. Relevant equations 3. The attempt at a solution I tried to use conservation of energy first i.e., 1/2*m*Vo^2 - GMm/R = 2GmM/3R 3R/2 - distance between planet's surface and apogee). Needless to say, that doesn't yield the right answer, I was wondering perhaps elliptical orbits have some other requirements -- perhaps the inclusion of angular momentum? Thanks, I appreciate any nudge towards the right direction.