Re: weight of a bird in a cage

[brian whatcott <inet@INTELLISYS.NET>]

Ludwik and Mark had a question about a crucial experiment of the
'bird in a box' variety that Jim described. (Quoted below)

    The purpose of Jim's description was to demonstrate that the
weight of a box plus flying animal is unchanging, momentary
excursions excepted.

   The problem with Ludwik's query, is that it asks if the box
+ animal weight remains constant plus or minus the animal's weight.

The answer to which is "Yes of course, whether it decides in favor
or against either of the following positions":

"the flying animal's weight reacts on the floor" OR
"The flying animal's weight is NOT reacted on the floor".

Hence, I deduce that Ludwik's question went unanswered because
an answer to his question would not contribute anything meaningful
to the discussion.

 I am quite certain that this is not the response Ludwik meant
to invoke. But I cannot read his mind, only his words.

One other thought: it is quite possible that one or more people
on this list is compensated for valuable steering and direction.
 But I expect that the great majority of the 500+ readers of this
list reads it voluntarily.

   They would not feel obliged (I imagine) to interact in any way
that did not meet their desires. Indeed, there may well be personal
reasons for resisting the temptation to post to a list discussion.
 What if I make a fool of myself? I almost hear them say...

 As an example, I noted on this list in the last week that the current
"American Scientist" carries a piece on the Tacoma bridge design.
It doesn't. I confused it with some popular science magazine.
   But I don't feel upset that nobody corrected my error.

On the other hand, the September/October issue of Am Scientist does
carry Krantz's piece on conformal mappings, which, inter alia,
discusses transforming streamlines of air flowing round a disk onto a
flow past an airplane wing (pp 440-1).

  However, perhaps I am mistaken again in this attribution - or
perhaps readers of this list do not read Am Scientist, or perhaps
they have taken the precaution of filtering out my contributions?
(If not yet, then soon, if I continue in this vein   :-)

At any rate, I hope this response is somewhat helpful.

Brian
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At 15:00 9/5/99 -0500, Ludwik wrote:
> After reading Jim's message (see below) I asked:
>
> > Are you saying that the net weight of the "box with the
> > fly inside" remained nearly constant (+ or - the weight
> > of 0.1 mg) no matter what the fly was doing?
>
> Jim Ealy wrote:
>
> > > a box from dry-cleaner's
> > > plastic wrap and balsa - total was less than 20 grams about 50 cm by 50
> > > cm. A closed system sealed with tape, after fly was inserted - positive
> > > pressure. ... They placed the
> > > fly in the "box" and placed it on a top-loading balance: 0.1 mg. ...

> > > Jim Ealy
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I too am waiting for a reply to Ludwik's question. Jim's description of his
experiment has an ellipsis (intentional or not) at the point indicated by
Ludwik, and I'd like to know exactly what he means to say.

Mark

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brian whatcott <inet@intellisys.net>
Altus OK