Working out an orbital period, given constants (earth's radius and GM) and average altitude

Question

I am having some trouble figuring out a formula for a JavaScript coding exercise.

Given a GM of 398,600.4418, earth's radius of 6,367.4447, and an average altitude of 35,873.5553, I must return an answer of 86,400.

I have experimented with the formula shown here but I cannot figure out how the average altitude comes into the equation, nor how to work out SMa³.

I just need a hint or two to help me understand the formula. Many thanks.

From 2019 -> thanks, I'm also solving the freeCodeCamp challenges :) — Alexander Popov, Feb 27 '19 at 15:31
@AlexBG Best of luck, I have been a front end dev for 3 years now after completing FCC :D — alanbuchanan, Mar 01 '19 at 09:09

score 5 · Accepted Answer · answered Sep 10 '15 at 17:12

5

If the orbit is circular, then $a$ in that formula is the orbital radius, which is the sum of altitude and Earth's radius.

answered Sep 10 '15 at 17:12

1 Answers1