From: fortunati.luigi@gmail.com   
      
   Circular motion without centripetal force is impossible.   
      
   And then we must find a plausible explanation for this case.   
      
   There is a rotating table and a disc without friction.   
      
   If a person in the laboratory gently lays the disk on the rotating=20   
   table and if the friction is (really) 100% absent, the disk, in the=20   
   absence of friction, can not be dragged from the table, so it remains=20   
   still while the table turns downstairs without disturbing.   
      
   For the observer who rotates with the table, the disk travels around a=20   
   circle without ever moving away or nearing the center of rotation.   
      
   How can we justify the rotary motion in the accelerated reference if no=20   
   centripetal force acts on the disc?   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)