On July 19, 1969, Apollo II's orbit around the moon was adjusted to an orbit of 111 km. The radius around the moon is 1785 km and the mass of the moon is 7.3 E22 kg.
a) How many minutes did it take to orbit once? (A: 120 min)
b) At what velocity did it orbit the moon? (A: 1600 m/s)

Question

On July 19, 1969, Apollo II's orbit around the moon was adjusted to an orbit of 111 km. The radius around the moon is 1785 km and the mass of the moon is 7.3 E22 kg.
a) How many minutes did it take to orbit once? (A: 120 min)
b) At what velocity did it orbit the moon? (A: 1600 m/s)

anonymous · Answer

Get the orbit radius by adding 111 km to the moon's radius. 

Can get the force from 
F = G m M/r^2
Set it equal to centripetal force, m v^2/ r
Setting them equal eliminates the mass m of the satellite,
and you can calculate the velocity, v..

Get the length of the orbit from the circumference, 2 pi r, and divide this length by the velocity to get the time needed.

kittiwitti1 · Answer

Oh.... but I already turned this in... I'll save it for another time to look at. (: