AP Physics C 2017

35 . D —Kepler’s third law states that for all planets in the same system, their period of orbit squared
is proportional to the average distance from the sun cubed. Using units of years and AU, for Earth, (1
year)^2 = (1 AU)^3 . For Mercury, we have (^1 / 5 year)^2 = (? AU)^3 . Solving for the question mark, you
find that the distance from Mercury to the sun is the cube root of ^1 / 25 AU, which is closest to ^1 / 3 AU.