Two identical planets orbit a star in concentric circular orbits in the star's equatorial plane. Of the two, the planet that is farther from the star must have
A) the smaller period.
B) the greater period.
C) the smaller gravitational mass.
D) the larger gravitational mass.
E) the larger universal gravitational constant.

Question

Quizplus · Accepted Answer

According to Kepler's Third Law, the period of a planet's orbit is proportional to the distance it is from the star. Thus, the planet further from the star will have a greater period. The mass or universal gravitational constant of the planets are not relevant in this scenario.

Two Identical Planets Orbit a Star in Concentric Circular Orbits