From: fortunati.luigi@gmail.com   
      
   Tom Roberts il 10/12/2023 11:52:28 ha scritto:   
   > On 10/23/23 6:31 AM, Luigi Fortunati wrote:   
   >> [...]   
   >   
   >      [The context of this question is clearly Newtonian mechanics.   
   >       But my answer holds for relativistic mechanics as well.]   
   >   
   > To definitively answer the question "is inertia a vector", one must find   
   > "inertia" in some equation(s). Unfortunately, "inertia" does not appear   
   > in any equation of mechanics. So the question is meaningless, or at   
   > least unanswerable.   
   >   
   >      [This includes Newton's original "vis insita".]   
   >   
   > Note: do not be confused by "moment of inertia" -- look at its   
   > definition and you'll see it is misnamed, and is really the second   
   > moment of mass.   
   >   
   > In modern physics,the closest quantity to "inertia" is mass, which is   
   > clearly a scalar (i.e. not a vector).   
   >   
   > Tom Roberts   
      
   What is mass for you?   
      
   If for you mass is just a quantity of matter, you are right: it is a   
   scalar, because it has no direction.   
      
   Instead, if the mass is an inertial body or a body that reacts, it has   
   direction.   
      
   In fact, the inertial body moves with uniform rectilinear motion (and   
   the motion is a vector) and the body that reacts exerts an opposing   
   force (and the force is a vector).   
      
   This is why inertia is a vector: because it moves in only one direction   
   or reacts in only one direction.   
      
   Luigi Fortunati   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)