From: fortunati.luigi@gmail.com   
      
   Luigi Fortunati lunedì 29/04/2019 alle ore 16:03:38 ha scritto:   
   > The second principle F=ma states that if we apply the net force F   
   > to  the mass  of the wheeled cart, the cart accelerates.   
   >   
   > And so far we all agree, I think.   
   >   
   > Is the opposite also valid? In other words, is it correct to say   
   > that  if NONE applies force to him, the trolley does NOT accelerate?   
      
   If you are blindfolded on a bus and ask you if it is accelerating or   
   not, you do not need to ask "accelerating in relation to whom?": Answer   
   that it is accelerating if you feel the force and answer that you are   
   not accelerating if you do not perceive it.   
      
   The difference between speed and acceleration is precisely this: speed   
   does not depend on strength (and therefore no one can tell bandied eyes   
   if there is or isn't) and instead acceleration DEPENDS on strength (and   
   therefore yes can say blindfolded if there is or not because the force   
   is PERCEIVED).   
      
   The acceleration NOSTRA we perceive internally to ourselves, for the   
   SAME reason why we directly perceive the force that determines it.   
      
   Ps. Attention: I'm talking about the acceleration of the bus and nothing   
   else.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)