Re: Breaking sticks or spaghetti

[Richard Grandy <rgrandy@ruf.rice.edu>]

At 12:27 AM -0500 1/30/98, Herbert H. Gottlieb wrote:
> JBRAUNSDORF@delphi.com writes:
> > When one takes a light stick or a piece of uncooked spaghetti and
> > holds it near the ends and flexes it it sometimes does not break into
> two pieces but
> > into three.  You end up with one piece in each hand and a short middle
> > section which flies off as a projectile.
> > .......  Unless they are somehow constrained to be simultaneous it seems
> that the >first break would relieve any stress on the remaining free end
> so it should not break a piece off.      Any clues would be appreciated.
>
> This question would make a nice student project using high-speed
> photography. I suspect that she would observe that the two breaks are NOT
> simultaneous.  The entire spaghetti strand is under great stress before a
> break occurs. After that first break, the stress is relieved and the
> remaining section attempts to relieve the stress by reverting to its
> original straight-stick spaghetti configuration. While doing so, there is
> a bound to be a whiplash effect with the free end travelling much faster
> than the rest of the stick.   If my theory is true, photographs should
> show that the section broken off from the middle of the stick rotates as
> it flies off to spaghetti heaven.
>
> Herb Gottlieb from New York City
> (Where we have the best spaghetti restaurants outside of Italy itself)
I don't remember the explanation, but I believe I remember a Scientific
American article many years ago on the fact that if you drop a piece of
chalk it frequently breaks into 3 pieces.  There was also some surprising
fact about the relative length of the pieces.

Richard Grandy