Here's some stuff I found:
http://en.wikipedia.org/wiki/Centrifugal_force
http://regentsprep.org/Regents/physi...if/centrif.htm
http://www.infoplease.com/ce6/sci/A0811114.html
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If you go by these sites they seem to say it's a "false force"....or "reactive force." I think reactive force is more appropriate.
Although.....you prolly could also get into the definition of "force" and what it means exactly....
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Makes sense though.....the centrifugal force is only there because there is something that is creating it....I guess that would be centripetal force...the actual rotation....which creates the centrifugal force.
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Really though....
Even if this is the way it is.....is does little to devalidate TGM in a working sense......more of a semantics thing or w/e.....all it would change is the definition itself.....add centripetal into the mix.