From: pa@see.signature.invalid   
      
   Mikko  wrote:   
      
   > Note that a wave from a small source (the first impact) sperad in all   
   > directions. In this case the wave reflects from the suface of the first   
   > shere and a large part of it arrives to the contact of spheres 1 and 2   
   > withing suffient short time to contribute to the impulse given to the   
   > second sphere. A part of the wave misses the contact with ephere 2   
   > and all the time the wave is attena=C3=BAated by the internal friction.   
   > Therefore force in each contact is smallter than in the previous contact   
   > and the motion gradually slows down.   
      
   I'm not sure the shape of the balls is critical to focusing the wave.   
   It should work as long as the balls are made of an extremely stiff   
   material.   
      
   A small fraction of the impulse is *not* transmitted all the way   
   to the end ball. The rest gets spread among the other balls and   
   they eventually oscillate together as a group (before the oscillations   
   die out).   
      
   --   
   pa at panix dot com   
      
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