All of the following hypothetical planets orbit a star with the same mass as the Sun (one solar mass). Which one has the shortest orbital period? (If two objects would have the same orbital period to within a difference of less than 1% consider them as having identical periods.)
A) Planet A: one Earth mass and 1 AU from the star
B) Planet B: two Earth masses and 1 AU from the star
C) Planet C: two Earth masses and 2 AU from the star
D) Planets A and B
E) Planets B and C F) All of them have the same period.

Question

Quizplus · Accepted Answer

According to Kepler's third law, the orbital period of a planet depends only on the semi-major axis of its orbit, not its mass. Therefore, Planets A and B, both at 1 AU, have the same shortest orbital period.

All of the Following Hypothetical Planets Orbit a Star with the Same