A comet of mass m is in an elliptical orbit around a star of
mass M. At the closest point of its orbit, point P, the comet
is a distance D from the center of the star, and at the farthest
point, point A, the distance is 3D. You may disregard the
presence of all other celestial bodies.
Derive an expression for the change in the comet’s kinetic
energy as it moves from point P to point A, in terms of
system parameters and constants.
Does the comet have its greatest speed at point A or point P?