From: julio@diegidio.name   
      
   On Wednesday, 13 July 2022 at 11:50:42 UTC+2, 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.   
      
   What matters is not really how we get there, just the steady state is   
   of interest, by which I mean the water is at rest relative to the bucket.   
      
   > But the centrifugal force is ONLY in the rotating reference and not in   
   > the inertial one.   
      
   There is in fact a corresponding centripetal force in the inertial frame   
   in which the bucket is rotating, which amounts to a combination of the   
   pressure forces ultimately sustained by the walls of the bucket, and   
   of course the gravitational force: hence it's obliquus.   
      
   > So, how is the centrifugal acceleration of water justified EVEN in the   
   > inertial reference where the centrifugal force is not there?   
      
   That should be clear now.  That said, the point with Newton's bucket   
   (as I get it) is that, in the reference frame *of the bucket*, where does   
   the apparent *centrifugal* force come from?  Since, by relativity, the   
   situation should be totally equivalent to the universe rotating around   
   a bucket at rest...   
      
   Julio   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)