From: rwi@whidbey.com   
      
   On 11/15/2017 1:50 PM, Luigi Fortunati wrote:   
   > Tom Roberts mercoled=C3=AC 15/11/2017 alle ore 09:16:36 ha scritto:   
   >> The reaction to the centripetal force of the above rope   
   >> pulling on the stone is simply the tension of the rope pulling on the ha=   
   nd.   
   >   
   > The tension of the rope pulling on his hand would not exist if there   
   > was not a rock FORCE on the rope to make it "tense".   
   >   
   >> But you also seem to be confused about the reality of   
   >> "centrifugal force" and the utter impossibility of it to "cause" anythin=   
   g.   
   >   
   > Centrifugal force causes (for example) the "real" effect of the Earth's   
   > crushing to the poles and its enlargement to the equator.   
   >   
   Perhaps an historical perspective would help.  Why does the term   
   "centrifugal force" even exist?  Before 1960-ish the basis of both   
   statics and dynamics were the same: the vector sum of all forces must   
   equal zero.  Obvious in the case of statics.  If the forces aren't   
   balanced, the object will accelerate and it's no longer a statics   
   problem.  For dynamics, to balance the equation it was necessary to add   
   virtual forces to account for acceleration.  Thus, centrifugal force,   
   Coriolis force, etc were negative virtual "forces" that that were really   
   accelerations.  Later, dynamics was changed to say that the vector sum   
   of all forces is equal to the accelerations times the mass.  Do both   
   method yield the same results?  Sure, but the later method causes less   
   confusion.   
      
   The term "centrifugal force" is obsolete and should be removed from the   
   lexicon but words, once in the language, remain for a very long time.   
      
   It does say "force" and everyone knows forces are real.   
      
   Richard   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)