[continued from previous message]   
      
   the ice.  That is, $Ilow$ is pushing up on $Ihigh$ with a (compression)   
   force $vF5$, and $Ihigh$ is pushing down on $ILow$ with a (compression)   
   force $F6 = -F5$.   
      
   If $g$ is nonzero (e.g., if we're on the Earth's surface), then, looking   
   at the equations for $F5$ and $F6$, we see that these compression forces   
   are *non-uniform*, i.e., $F5$ and $F6$ vary with the height $x$: at $x=0$   
   (the bottom of the ice) $F5$ and $F6$ have their maximum magnitudes; at   
   larger heights $x$ both forces decrease (linearly with the height $x$),   
   and at $x=L$ (the top of the ice) $F5 = F6 = 0$.   
      
      
      
   As you can see, the analysis of the vertical-ice system was basically   
   identical to the analysis of the horizontal-ice system, with the   
   vertical-ice gravitational acceleration $g$ playing the same role as   
   the horizontal-ice acceleration $a = F_ext/m_ice$.  This is "just" an   
   example of Einstein's equivalence principle at work: an accelerated   
   reference frame can equivalently be viewed as stationary in a uniform   
   gravitational field.   
      
   --   
   -- "Jonathan Thornburg [remove -color to reply]"    
      (he/him; currently on the west coast of Canada)   
         "Liz Holmes didn't go to jail because she deceived people. She went to   
          jail because she deceived the wrong people."   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)