Consider a hypothetical planet in our solar system whose average distance from the Sun is about four times that of Earth. Determine the orbital period for this hypothetical planet.
A)0.25 year
B)2.5 years
C)4 years
D)8 years
E)16 years

Question

Quizplus · Accepted Answer

Kepler's third law states that the square of the period of an orbit is proportional to the cube of the average distance from the Sun. 
So if the average distance from the Sun is four times that of Earth, then the cube of the distance ratio (4^3) is equal to the ratio of the periods squared. 
Therefore, (4^3) = (period of hypothetical planet)^2 / (period of Earth)^2. 
Solving for the period of the hypothetical planet gives us the square root of 64, which is 8. So the orbital period for this hypothetical planet is 8 years.

Consider a Hypothetical Planet in Our Solar System Whose Average