Imagine a spherical, nonrotating planet of mass M, radius R, that has no atmosphere. A satellite is fired from the surface of the planet with speed vo at 30 degrees to the local vertical. In its subsequent orbit the satellite reaches a maximal distance of 5R/2 from the center of the planet. Using the principles of conservation of energy and angular momentum, show that vo - (5GM/4R)^1/2 This is what I've done so far and it's not right: E=1/2 mv^2 - GMm/2R = GMm/4R 1/2mv^2-GMm/2(5R/2) = GMm/4(5R/2) 1/2mv^2-GMm/5R = 2GMm/20R 1/2v^2 = 3GM/10R .:v = (3GM/5R)^1/2 Clearly, this isn't the answer I should be getting. Does anybody know where I'm going wrong?