The period of the moon is approximately 27.2 days. Determine the radius of the moon's orbit and the orbital speed of the moon.

Question

ivancsc1996 · Answer

Well which equations do you know about orbital movement?

anonymous · Answer

$$V =\sqrt{Gm divr}$$

anonymous · Answer

$$g=Gm/r^2$$

ivancsc1996 · Answer

Ok so the only real problem is finding the radius of the moon's orbit. But I can't find it with any of those equations. Don't they give you the gravitational force between the earth and the moon or a equation involving the centripetal force?

anonymous · Answer

$$Fc=mv^2/r$$
$$Fg=Gmm/r^2$$

ivancsc1996 · Answer

Well $$F _{c}=F _{g}=\frac{ mv ^{2} }{ r }=\frac{  Gm _{1}m _{2} }{ r ^{2} } \rightarrow r=\frac{ Gm _{1} }{  v ^{2} }$$But that is no different from the equation in the previous comments. I steel need something more.