From: ram@zedat.fu-berlin.de   
      
   Luigi Fortunati  writes:   
   > Centrifugal force causes (for example) the "real" effect of the Earth's   
   > crushing to the poles and its enlargement to the equator.   
      
     There are two definitions of "force":   
      
     1.) F1 = dp   
      
         Force is a change of momentum.   
      
     2.) F2 = g + e   
      
         Force is the sum of the gravitational force g   
         (determined - in simple cases - by two masses and their   
         distance) and the electromagnetic force e (determined -   
         in simple cases - by two charges and their distance).   
      
         ("g" and "e" here are my custom symbols, not symbols   
         in general use!)   
      
     When we assume that both definitions are valid,   
     we have F1 = F2, i.e.,   
      
         dp = g + e                                   (1).   
      
     I'd say that an inertial system is a system where this   
     equation holds. If it's however,   
      
         dp = g + e + s                               (2)   
      
         ("s" here is my custom symbols, not a symbol in   
         general use!)   
      
     with a non-vanishing term s, then s is an   
     "apparent" force. Of course s is just as "real" as   
     g and e issofar as it causes a change of momentum.   
      
     Of course, all of the above is valid only in a sufficiently   
     simplified model. For more elaborate world views, one might   
     be able to extend it using additional terms or to simplify   
     it by the removal of some terms.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)