A planet has a semimajor axis of 10 astronomical units.The orbital period would be
A)1.7 years
B)5.2 years
C)9 years
D)32 years
E)100 years

Question

Quizplus · Accepted Answer

According to Kepler's third law, the square of the orbital period (in years) is proportional to the cube of the semimajor axis (in astronomical units). Using this formula, we get: orbital period^2 = (semimajor axis)^3. Plugging in the values for semimajor axis (10 AU) and solving for the orbital period, we get: orbital period^2 = 10^3, so the orbital period is 32 years (approximately). Therefore, the correct choice is D.

A Planet Has a Semimajor Axis of 10 Astronomical Units