Consider a star with 2 planets. The mass of planet A is the same as the mass of planet B. The orbit of Planet A is on average, closer to the star than the orbit of Planet B. Which of the following statements is true?
A)Planet A moves with the same speed as Planet B.
B)Planet A is, on average, moving faster than Planet B.
C)The relative orbital speeds depend on the masses of the planets.
D)Planet A is, on average, moving slower than Planet B.

Question

Quizplus · Accepted Answer

According to Kepler's Laws of Planetary Motion, planets closer to the star have a smaller orbital period and therefore travel at a faster average speed than planets farther away. Since Planet A is on average closer to the star than Planet B, it must be moving faster. The masses of the planets do not affect their relative speeds in this scenario.

Consider a Star with 2 Planets