From: sylvia@email.invalid   
      
   On 14/01/2019 9:23 am, Luigi Fortunati wrote:   
   > 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   
   > table and if the friction is (really) 100% absent, the disk, in the   
   > absence of friction, can not be dragged from the table, so it remains   
   > still while the table turns downstairs without disturbing.   
   >   
   > For the observer who rotates with the table, the disk travels around a   
   > circle without ever moving away or nearing the center of rotation.   
   >   
   > How can we justify the rotary motion in the accelerated reference if no   
   > centripetal force acts on the disc?   
   >   
   >   
      
   You misstated the rule. It should be:   
      
   Circular motion without centripetal force is impossible in an inertial   
   frame.   
      
   An accelerated frame is not inertial.   
      
   Sylvia.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)