Question

A satellite orbits a planet at a distance of 3.80 108 m. Assume that this distance is between the centers of the planet and the satellite and that the mass of the planet is 3.90 1024 kg. Find the period for the moon's motion around the earth. Express the answers in days.

Answer 1

1) find the circumference (c=2(3.14)r)
2(pi)(3.8E8)= 2387610417m = 1 orbit/rev

2) find velocity v=√(G*M)/(r)
v=√(6.67E-11*3.9E24)/(3.8E8)=827.38m/s

3)convert velocity into m/days; so if there is 86400 seconds in a day...
827.38*86400=69996090.7m/days

4)divide the orbit/revolution by m/day

2387610417m/69996090.7= 34.111 days :)