From: fortunati.luigi@gmail.com   
      
   Sylvia Else alle ore 23:13:32 del 18/07/2017 ha scritto:   
   >>>> The BC stick is dropped vertically into an endless well.   
   >>>>   
   >>>> Let M be the midpoint between B and C.   
   >>>>   
   >>>> In this mental experiment, the  acceleration of M (relative to the   
   >>>> well) is constant.   
   >>>>   
   >>>> When the stick speed becomes relativistic, does the acceleration of   
   >>>> points B and C (always in the well reference) remain equal to  or   
   >>>> is it greater or lesser?   
   >>>   
   >>> We're not told which of B and C is the upper end.   
   >>   
   >>    Let B be the top and C the lower one.   
   >>   
   >>> However, the   
   >>> acceleration of the upper end is greater than that of M, and the   
   >>> acceleration of the lower end is less than that of M. Thus the stick   
   >>> gets shorter in the frame of the well (but not, of course, in the frame   
   >>> of the stick).   
   >>   
   >>    So ahead of B runs the shaft wall with greater acceleration than it   
   >> does run in front of C, right?   
   >>   
   >   
   > I'm not sure what you mean by that.   
   >   
   > Sylvia.   
      
     I mean that if the well reference is the points B and C that   
   accelerate, in the stick reference is the well that accelerates.   
      
   --   
   Luigi Fortunati   
      
   Credere e' piu' facile che pensare   
   Believing is easier than thinking   
      
   [[Mod. note -- I think what the author is trying to say is that   
   (1) in the (inertial) well reference *frame* the points B and C are   
   accelerating downwards, (2) in the (non-inertial) reference frame of   
   point B, the wall is accelerating upwards, and (3) in the (non-inertial)   
   reference frame of point C, the wall is accelerating upwards.   
   -- jt]]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)