Homework Statement
Planet X of mass mx = 2.1 × 1024 kg orbits S in uniform circular motion at a distance rx and with a period Px = 2.1 years (=66225600 s). The mass of the star S is MS = 2 × 1031 kg and its radius is RS = 3.2 × 108m.
Homework Equations
T=2pi * sqrt(r3/(GM)
The Attempt at a...