From: tjoberts137@sbcglobal.net   
      
   On 11/3/22 3:39 AM, xray4abc wrote:   
   > On Wednesday, July 13, 2022 at 5:50:42 AM UTC-4, Luigi Fortunati   
   > wrote:   
   >> When Newton's bucket starts to rotate, the water slowly starts to   
   >> rotate as well and accelerates outwards due to the centrifugal   
   >> force.   
      
     ... only in the rotating-bucket coordinates. In any inertial frame the   
   water does not "accelerate outwards", it merely tries to move in a   
   straight line -- in the rotating coordinates that is indeed accelerating   
   outward.   
      
   >> But the centrifugal force is ONLY in the rotating reference and   
   >> not in the inertial one.   
      
   Right. Ditto for any "centrifugal acceleration".   
      
   >> So, how is the centrifugal acceleration of water justified EVEN in   
   >> the inertial reference where the centrifugal force is not there?   
      
   It isn't justified, because it does not exist. You seem to be confusing   
   straight-line motion in an inertial frame with "centrifugal acceleration".   
      
   > In our ,that is exterior, reference frame...we realize that the   
   > water is forced into movement by the friction  between itself and   
   > the bucket.   
      
   Sure. That accelerates it both tangentially and radially inward.   
      
   Tom Roberts   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)