From: bells@infonode.ingr.com (Scott Bell)
Subject: Re: Power Volleyball - Cosmic Physics 
Organization: Intergraph Corporation, Huntsville, AL.
Distribution: usa
Date: Mon, 13 Apr 1992 21:17:25 GMT

>>In article <1992Apr10.170047.13370@infonode.ingr.com> bells@infonode.ingr.com (Scott Bell) writes:
>>] 
>>]      Putting topspin on a ball causes it to "shoot straight". A similar
>>]    example is the spiraled groove in a gun barrel, which does the same.
>>] 
>

  gene@wucs1.wustl.edu (Gene Van Buren aka "_Floor_") responds:

> Huh? Since when does one put TOPSPIN on a bullet? The helical grove
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

       Welp, looks like the Iraqi's tried w/ their SCUD DUDS! ;) ;)
         
> in a gub barrel serves to give the bullet rotation about its axis
> parallel to the direction of motion). This rotation brings about
> the gyroscopic effect which stabilizes the bullet and prevents it
> from "tumbling" through the air. Just try throwing a fribee without
> spinning it. The gyroscopic effect is really conservation of angular
> momentum, which is a vector quantity. Therefore, the axis of rotation
> doesn't want to change from its 'present' direction. Now, for a
> spinning volleyball, this means a ball with topspin tends to maintain
> topspin. It is not angular momentum that causes a ball to "shoot
> straight" necessarily, although it may be distantly related. Thus the
> above comparison isn't quite right IMHO.

      To quote you: "Huh?"

      I did muff it when I made the gun-spiral/volleyball-topsin comparison.
      But physics and dynamics aside, I was merely trying to relate spin
      w/ direction. A floater is NOT supposed to have any spin( or minimal )
      to cause the ball to "bounce" around much more than one w/out spin
      in ANY direction. Again, this is from practical experience outside of
      a particle accelerator( ;) ;) ), based on what I've seen and done. 

> But, to bring up an old issue, it is the lack of spin which takes
> stability away from a floater. This is why a floater can sometimes
> wobble through the air. Balls with spin (of any sort - and the more
> spin, the better) are often more stable and constant as they go
> through the air. But this goes for spin of any sort - not just top,
> side, or backspin. A bullet uses its particular rotation because
> its shape works well with that - topspin wouldn't work so well
> aerodynamically. A frisbee spins the way it does so that it retains
> the desired profile to the air. And volleyballs?.....hmmmm.

       Volleyballs ALWAYS retain their profile - it's the players that
       sometimes lose their own profiles! ;) ;)

>:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
>:Gene Van Buren________________Floor_::    gene@cs.wustl.edu               ::
>:     Particle-Physicist-To-Be       ::    gene@lechter.wustl.edu          ::
>:        Volleyball! Don't Catch It! ::    gene@camps.phy.vanderbilt.edu   ::
>:        NCAA Div. III Nat'l Champs  ::    gev1@cec2.wustl.edu             ::
>: "Back off, man...I'm a scientist!" ::vanburen%undhep.dnet@dirac.cc.nd.edu::
>:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::


 Get Vertical!
 Scott
_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_
|                                            .                         |  
| Scott Bell                                 | "Where do I go now      | 
| Intergraph Corp. - Mapping Sciences Div.   |   now that I've gone    |
| M/S IW17A2  Huntsville, AL  35894-0001     |   too far?"             |
| b17A.bell.scott@ingr.com   (Internet)      |      - WTBHTB           | 
| uunet!ingr!b17a!bell!scott (uucp)          |               /-__--\   |
| W: 205-730-1776                            |   [:::|=======| {} }|   |
|        #include <std_disclaim.h>           |               \_--__/   |
_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_