1. Asking because the answer I got seems too simple...a planet of mass m moves in an elliptical orbit about the sun. The minimum and maximum distances of the planet from the sun are called the perihelion and aphelion respectively. If the speed of the planet at p is vp, what is its speed at a? Assume the distances rp and ra are known. 2. Relevant equations dA/dt = 1/2r2ω, ω=v/r 3. The attempt at a solution dA/dt is constant, so 1/2rp2ωp = 1/2ra2ωa. Substitute v = ωr, that gives 1/2rpvp = 1/2rava, va = rpvp/ra. Is this correct?