Re: Satelite Motion

["Carl E. Mungan" <mungan@USNA.EDU>]

Bernard Cleyet wrote:

> L doesn't change?
>
> If L is measured WRT the center of the earth, yes.  But, is not the C of
> M of the system not at the center of the earth?  Is it appropriate, in
> this problem, to arbitrarily use the C of the Earth as the measure of
> L?  Doubling the Earth's mass will move the C of M of the system towards
> the C of the Earth.

That's a small correction:
M (earth) = 5.97e24 kg
m (moon) = 7.35e22 kg

Therefore distance from original CM to earth center ratioed to
earth-moon separation R is:
m/(m+M) = .012 originally
m/(m+2M) = .0061 new

Both of these can be neglected. If not, you're also going to have
worry about other small effects such as the noncircularity of moon's
original orbit. Carl
--
Carl E. Mungan, Asst. Prof. of Physics  410-293-6680 (O) -3729 (F)
      U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5040
mailto:mungan@usna.edu       http://usna.edu/Users/physics/mungan/