Kepler's third law relates the period P and the semimajor axis a of an orbit. For a circular orbit, P = 2 $\pi$a/v, so it is possible also to relate the speed at which the particle orbits, v, to a. The result is
A) as a increases, both P and v increase.
B) as a increases, P increases but v decreases.
C) as a increases, P decreases but v increases.
D) as a increases, both P and v decrease.

Question

Quizplus · Accepted Answer

Kepler's third law implies that the orbital period (P) increases with the semimajor axis (a), but the orbital speed (v) decreases as the distance from the focus of the orbit increases. This is because the gravitational force, which dictates the orbital speed, weakens with distance, leading to a slower velocity for objects in orbit at greater distances.

Kepler's Third Law Relates the Period P and the Semimajor π\piπ

Kepler's Third Law Relates the Period P and the Semimajor $\pi$