Re: [Phys-L] More on Gravity Waves

["Folkerts, Timothy J" <FolkertsT@bartonccc.edu>]

> > Suppose the ball M is pushed suddenly toward the ball m  (along the 
> > line connecting the two centers of mass).

> ...  It's called the /tide/.  

That doesn't sound like any definition of "tide" I have heard.  For example, wikipedia's 'Tidal force' page opens with:
"The tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational force exerted by one body on another is not constant across it; the nearest side is attracted more strongly than the farthest side."

The original example would work perfectly well with point masses.  Hence it is not a tidal force.  It is simply the GMm2/r^2 force between the centers of the two objects, with 'r' changing as one ball is repositioned.