Re: The Olympics

[Zach Wolff <zachary_wolff@YAHOO.COM>]

There seems to be general agreement from list members
that divers and gymnasts either leave the ground or
board with some angular momentum or perform
complicated gyrations, moving one half the body then
the other, to execute a mid-air twist.  My girlfriend,
a gymnast, argues that this is not so.  She claims
that it is important to leave the ground with no
rotation whatsoever and that move required to twist is
simply to draw both fists to the one shoulder and turn
the head toward that same shoulder, causing a rotation
in that direction.  I am unable to understand how this
could possibly cause the rotation in the intended
direction.  It is possible that her intuitions are
incorrect.  Only stroboscopic pictures would reveal
the truth.  However, her argument is strengthened by
two factors: one, she claims that leaving the ground
with any rotation leads to a point deduction and
judges are watching very carefully, two, she claims
that it is possible to decide which way to twist AFTER
leaving the ground.  She makes the same claims for
diving where she has some experience, but not at a
competitive level.  Can anyone make sense of this
data?

Zach



> On 24 September 2000 Justin Parke wrote:
> > Perhaps the answer to this question should be
> obvious to me, but after
> > pondering for a while have not been able to answer
> it.
> > It seems that the divers in the olympics (and the
> "trampoliners") are able to
> > execute  half-twists, beginning and ending the
> twist in mid-air.  I do not
> > know how they do this without violating
> conservation of angular momentum.
> > Could someone enlighten me?


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