A planet of mass M orbits a star in a circular orbit of radius R, with orbital period T. What would be the orbital period of another planet, orbiting at radius R, but having mass 2M?
A) 0.71T
B) T
C) 1.4T
D) 2T
E) 0.50T

Question

Quizplus · Accepted Answer

The orbital period of a planet orbiting a star in a circular orbit depends on the mass of the star and the radius of the orbit, not the mass of the planet. Therefore, doubling the mass of the planet does not affect the orbital period.

A Planet of Mass M Orbits a Star in a Circular