Re: Sodaplay: Tacoma Narrows resonator

[Chuck Britton <britton@NCSSM.EDU>]

At 5:31 PM -0800 12/7/00, Leigh Palmer,  you wrote about Re:
Sodaplay:  Tacoma Narrows resonator:
>  >4. What mechanism started and supported  the oscillations of that bridge?
>
> The bridge deck, initially more or less having the wind velocity
> in-plane, got a little bit out of plane and the wind reinforced
> this distortion. A vortex was shed, allowing the distortion to
> relax and, it turns out, overshoot its equilibrium position, at
> which time the opposite polarity distortion is driven to
> increase by the wind until another vortex is shed, the deck
> relaxes past equilibrium, usw. When the wind was gentler, this
> oscillation did not grow in amplitude to bridge failure, which
> gave the bridge its nickname of "Galloping Gertie".


But let's not think that the vortex shedding was a sympathetic
driving force for the oscillations, because THAT would break down
this VERY tenuous distinction  ;-)


By the way, my copy of the LBNL & CERN Particle Physics Booklet has a
little section on the Breit-Wigner equation which relates amplitudes
of 'resonances' to their energy and 'elastic' width.

I THINK these MIGHT be related to a free particle passing over a
quantum well and experiencing an interaction related to the
properties of the well.

I just want to know how 'Sympathetic Vibrations' relate to these resonances.

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Chuck Britton                                   Education is what is left when
britton@ncssm.edu                               you have forgotten everything
North Carolina School of Science & Math         you learned in school.
(919) 286-3366  x224                            Albert Einstein,        1936