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

Question

Quizplus · Accepted Answer

Kepler's third law states that the square of the orbital period (P) is proportional to the cube of the semimajor axis (a). As a increases, P increases. For a circular orbit, v = 2πa/P, so as a increases and P increases, v must decrease.

Kepler's Third Law Relates the Period P and the Semimajor