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Re: weight of a bird in a cage



At 12:42 9/2/99 -0400, Jim Ealy wrote:
Listmembers;

My nature always says go to the lab when I hear "opinions" (I know that
places me several rungs down THE ladder)

My high school students several years ago made 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. We waited until spring to capture one of those large flies
(commonly called - casement flies) that emerge in rooms. They placed the
fly in the "box" and placed it on a top-loading balance: 0.1 mg. There is
no question about what happens (flying,landing, starting off from bottom
or side or top (or repeating after punching holes in plastic for air to
move in or out as in an open system)). "It" only becomes difficult when we
as teachers try to make "it" more than "it" is.
................butterflies "work" well also.
Jim Ealy
Education by Demonstration


I salute Jim for this most pertinent account.
And I sincerely hope he is showing only a
becoming modesty about the pre eminent place
of experiment, and of experimenters on the
rungs of the Physics ladder.

On this thread or an allied topic, I also meant to answer the
question, how would a wing behave in a liquid?

Apologizing for not having the name of the person who asked
this question first, I simply note: it has been the practise of
some airplane designers to fly small models of their designs in
swim pools, where they glide through the water rather slowly,
in a way that can provide insight to an engineer.

There are of course various scaling rules ('laws') that can
provide an intellectual bridge beween fluids of the
airy vs runny kind.







brian whatcott <inet@intellisys.net>
Altus OK