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SAT® Subject Test in Physics

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Planetary Orbital Period

SATPHY-GGJF7V

Two planets (planet $X$ and planet $Y$) orbit the same star with uniform circular motion. Planet $X$is three times as far from the star as planet $Y$.

How many times longer does it take planet $X$ to orbit the star compared to how long it takes planet $Y$ to orbit the star?

A

3 times as long.

B

9 times as long.

C

27 times as long.

D

More than 27 times as long.

E

The relationship between period and orbital radius is such that it will not give us an integer result.