[Phys-L] Re: Science "Magic" Demos

[jbellina <jbellina@SAINTMARYS.EDU>]

Take a glass funnel...a small one that a pingpong ball will fit in,
and with a long stem if you can.  Put the ball in the upright funnel
and ask if the ball will come out of the funnel, then turn it over
and ask the same question...everyone knows.  Then ask what would
happen with the upside down funnel if you sucked on the stem...would
the ball stay in...they will say yes.  Then ask what will happen if
you blow in the stem.  Most will say the ball will fall.  Then try it.

I have always liked dropping a ball and a feather in air and in an
evacuated tube.

If you have a large concave mirror you can create a nice illusion of
a bulb in an empty socket by projecting the real image of an inverted
bulb onto an empty socket.

cheers

Joseph J. Bellina, Jr. Ph.D.
Professor of Physics
Saint Mary's College
Notre Dame, IN 46556

On Sep 27, 2005, at 4:00 PM, Folkerts, Timothy J wrote:

> I volunteered to give a ~ 50 min presentation on "science magic" to
> ~20-30 high school students in about 3 weeks and was hoping some
> people
> here had some favorites they might like to share.  Hopefully the demos
> will be 1) entertaining, 2) educational, 3) low budget and 4) not too
> difficult to perform.  I plan to present a brief explanation of each
> feat, but no really involved derivations or anything like that.
>
> Some current ideas include
> 1) bed of nails (I'd have to build one soon)
> 2) string tied above & below a heavy weight (slow pull breaks top
> string, quick tug breaks bottom string.
> 3) cabbage juice pH indicator.
> 4) juggling on a force plate (showing that the average force is the
> same
> whether juggling or not)
> 5) Bernoulli ping pong ball suspended on a stream of air.
> 6) cooling & crushing a container full of steam
>
> Do these sound reasonable?  Any other ideas?  Links to website with
> similar info?  I don't think these will take 10 min each, so I need a
> few more!
>
> Thanks in advance.
>
> Tim Folkerts
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