### Re: ZetaTalk and Spaceguard UK (D8)

```Greg Neill wrote:
>> Then lets plug that CONSTANT into both equations, which
>> should come up with the same VELOCITY for the Moon (which
>> it won't and Greg will go off blustering).  Restated, then, the
>> problem is to put it all on the same page, using same units of
>> measure for MASS.
>
> The simplest way to approach the problem is to equate the two
> forces that are in balance in such a system, namely the
> gravitational force and the centrifugal force (that pseudo-force
> which is the result of inertia for a body experiencing uniform
> circular motion).  Thus:
>
>     Force due to gravity is    F1 = G*M1*M2/r^2
>
>     Centrifugal force is       F2 = M2*v^2/r

But you're not doing what you SAID you were doing.  If the force of
gravity is a factor of BOTH gravitational masses, increasing as the size
of these masses increases and the distance between then decreases, per
Newton, then why should the Centrifugal force NOT have to consider that
force?  Put BOTH those Newton laws together.  Plug in not a SINGLE mass
factor into Newton's Centrifugal force formula, but the force of gravity
per Newton!  The Moon is having to overcome, with its velocity, a
greater gravity pull than the satellite.

Is there a Newton formula for velocity for a HIGH mass orbiting object?
Magnus mentioned the equation provided for satellites as a "low-mass
object".  What's the formula for a high-mass orbiting object?

Magnus Nyborg wrote:
> Orbital speed for ideal circular motion of a low-mass object
> circling a high-mass object M (which refers to it's mass) is
> determined by the formula
>
>   v = sqrt( G*M / r )```