From: poutnik@privacy.net   
      
   Dne 13/11/2017 v 06:58 Luigi Fortunati napsal(a):   
   > Centrifugal force is an "apparent" force.   
   >   
   > Ok, but I have a doubt and I hope you can clarify it.   
   >   
   > The sling rotates and the hand exerts a real centripetal force on the   
   > rope.   
   >   
   > For the third principle, even the rope exerts an equal and opposite   
   > force (hence centrifuge) on the hand.   
   >   
   > How is possible that the two opposing forces, one is real and the other   
   > apparent?   
   >   
   This centrifugal force is a normal reactive force.   
      
   What is meant as centrifugal force being apparent force   
   is in the context of non inertial, rotating coordinate systems (CSs).   
      
   There exists 3 apparent forces in rotating CSs.   
      
   Coriolis force, related to ther object velocity.   
   Centrifugal force, related to the object distance to the axis.   
   Euler force, related to the CS angular acceleration.   
      
   Additionally, there can be other apparent forces   
   related to the acceleration of CS centre   
   or to tilting of the rotation axis.   
      
   --   
   Poutnik ( The Pilgrim, Der Wanderer )   
      
   A wise man guards words he says,   
   as they say about him more,   
   than he says about the subject.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)