Re: Sodaplay: Tacoma Narrows resonator

[Leigh Palmer <palmer@SFU.CA>]

> 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  ;-)

Definitely not. The vortex shedding frequency of the static bridge
is not the same as the frequency of the normal modes of the bridge.
The vortex frequency only reaches the normal mode frequency after
the oscillation begins. Are you suggesting that the bridge drives
a resonance in the atmospheric system?

I have great difficulty understanding the death grip some folks
have on calling this phenomenon a resonance. What is the practical
value in doing so? All that is accomplished if one admits this new
meaning is that the meaning of the term becomes less precise. The
only benefit seems to be that the Tacoma Narrows Bridge film can
then be shown as an example of that other meaning.

This should be looked upon from the point of view of the student
on whom this example is inflicted. How can she reconcile this with
the experiment she does in the lab with a VFO and an RLC circuit?
Where's the connection? It is my feeling that this connection,
however tenuous it might be, is *never* made in teaching.

Leigh