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Re: Center-of-mass system



Well, I think I can. The center of gravity of a rod is the point where
0 = Integral over length of rod (dl l.g) where l is the vector from the
point, g is the gravitational acceleration vector, and the dot product
is indicated. In John's example the c.g. is a property of the rod's
placement, rather than a property of the rod.
regards,
Jack

Adam was by constitution and proclivity a scientist; I was the same, and
we loved to call ourselves by that great name...Our first memorable
scientific discovery was the law that water and like fluids run downhill,
not up.
Mark Twain, <Extract from Eve's Autobiography>

On Thu, 13 Apr 2000, John Mallinckrodt wrote:

On Thu, 13 Apr 2000, Leigh Palmer wrote:

Of greatest importance is that one should *never* allow the use of
"center of gravity"! There is no case where this atrocious construct
is more appropriate than "center of mass".

Indeed. In fact, leaving completely alone any question of its usefulness,
I have often wondered if there can even *be* a reasonable, general
definition of "center of gravity." For instance, consider a uniform thin
rod with a length equal to the radius of Earth tangent to Earth at one
end. Can somebody tell me where the center of gravity is and what
definition you are using?

John Mallinckrodt mailto:ajm@csupomona.edu
Cal Poly Pomona http://www.csupomona.edu/~ajm