From: poutnik@privacy.net   
      
   Dne 14/11/2017 v 07:46 J.B. Wood napsal(a):   
   > On 11/13/2017 12:58 AM, Luigi Fortunati wrote:   
   >> 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?   
   >>   
   >   
   > Hello, and according to Isaac Newton, for every action there is an equal   
   > and opposite reaction.  A mass that is forced to rotate about a central   
   > point as a result of gravity, a rope, etc, is experiencing a continuous   
   > change of momentum (a quantity having both magnitude and direction).   
   > The mass is accelerating towards the center, which means a force is   
   > being applied to the mass.  (An unconstrained mass would travel in a   
   > straight line.)  I think the term "reaction" vs "apparent" is more   
   > accurate in describing centrifugal or other such forces.  Sincerely,   
   >   
   ... and while in an inertial coordinate system   
   the centrifugal force is the real reactive force,   
   in the rotating coordinate system   
   it is a fictitious/apparent force.   
      
   In the latter, there must be acting real force   
   of the same magnitude but opposite direction   
   against the fictitious force to keep an object in the rest.   
      
   --   
   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)