From: pastgio@units.it   
      
   Il 02/11/22 09:04, Tom Roberts ha scritto:   
   > On 11/1/22 2:44 AM, xray4abc wrote:   
   >> Centrifugal forces  in rotational reference frames are not active   
   >> forces  but reactive forces.   
   >   
   > No. Here's why:   
   .   
      
   ... "centrifugal, Coriolis, and Euler forces" -- these are purely   
   > artifacts of using the rotating coordinates. They are not real in any   
   > sense of the word, and they are not "reactive", they are FICTIONS   
   > created by human mathematics in order to permit a human analyst to act   
   > as if Newton's laws applied in the rotating coordinates.   
   >   
   >       [Note: I put "centrifugal, Coriolis, and Euler forces" in   
   >        "scare quotes" because those names are inappropriate and   
   >        lead all too many people to error. They are not really   
   >        forces, they are imaginary constructs of human minds.   
   >        But the names are solidly established historically.]   
   ....   
     The "centrifugal force" is purely   
   > an artifact of the mathematics of using rotating coordinates -- mental   
   > constructs of humans are not real.   
      
   It is an endless debate about the status of the so-called fictitious (or   
   inertial) forces. Saying that they are "purely artifacts", "not real in   
   any sense of the word", "imaginary constructs", amd so on, risks to   
   create at least as many misunderstandings as such statements would like   
   to avoid.   
      
   It is a fact that such "imaginary constructs" are routinely used in   
   weather forecast, balistic, and other real life activities. It is   
   pedagogically wrong to convey the idea that such things do not exist.   
      
   The key point every consideration about such topics should start  with a   
   clear statement about the definition of force he/she is using.   
      
   If we define "force" only the quantity causing acceleration as a   
   conesquence of the interaction between differen bodies, certainly   
   "inertial forces" are not forces. If we follow Mach's point of view,   
   defining force through F-ma, they are. The choice between these two   
   points of view it is largely matter of taste, provided one sticks to a   
   well definite conceptual framework.   
      
   Whatever is the definition, it is also a fact that at the end of the   
   day, what really matters is the expression of the acceleration of one   
   body in terms of all the relevant variables. It is again a fact that,   
   whatever is the name we give to such espression, newtonian dynamics   
   allows to maintain the same mathematical structure of second order   
   ODE's, even if decide to describe the motion in a non-inertial system.   
      
   I think this is the really important fact. Decisions about the naming   
   conventions are irrelevant for the formal and numerical results.   
      
   To come back to Newton's bucket, the ability of describing what happens   
   in terms of inertial an non-inertial reference frames is an useful   
   conceptual exercise, independently of the names assigned to different   
   formal ingredients.   
      
   Giorgio   
      
   --- SoupGate-Win32 v1.05   
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