Re: weight of a bird in a cage

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

Mark Sylvester wrote:
> Brian points out that Ludwik screwed up his question (and I didn't read it
> carefully enough), but I really would like to know what Jim meant. Maybe
> I'll just catch some flies and weigh them.

I have no idea where I screwed up; perhaps I lost a message which was
criticizing me. In any case, I no longer applaud Jim Ealy who posted a
description of an experiment and does not want to provide clarifications.
I suspect that ... (never mind).

Today I caught a wasp (mass=77.8 +/- 0.1 mg) and placed it into a styrofoam
box of mass 7066.2 +/- 0.1 mg. The box was placed on the top-loading digital
scale. The three readings of the scale for the box without the fly were: 7066.2
7066.1 and 7066.3 mg (after placing the box on the scale 3 times). With
the fly inside the readings fluctuated by as much as 10 mg (without touching
the box).

Unfortunately the insect did not want to fly in my small box. It crawled and
perhaps agitated air with its wings (the box had holes). I could not watch it
through a small cellophane foil and read the scale at the same time.

Other people promised to perform experiments. I will be waiting for their
descriptions. I am too busy with many things right now.
Ludwik Kowalski

Here is Jim's original message and my question. Where did I screwed up?

> 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:

> > 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