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

[cliff <cparker@CHARTER.NET>]

Get a new flat sheet of paper.  Place it on a table so that maybe an inch
hangs out over the edge of the table.  Stand a new unsharpened pencil
upright at the back edge of the paper maybe one inch from the edge.  Ask
audience members to pull the paper out from under the pencil without tipping
the pencil over.  Unless they have seen it done or are very clever they will
not be able to do it because they will grab the paper and try to pull as
fast as they can with their hand starting at rest.   Now you do it by
starting your hand moving from behind and to the side of the paper.  Bring
your hand into contact with the paper on the way by the pencil and let the
friction of your hand on the paper move the paper.  With just a little
practice you will be an expert.  Newton's laws are all over this demo.

----- Original Message -----
From: "Folkerts, Timothy J" <FolkertsT@BARTONCCC.EDU>
To: <PHYS-L@LISTS.NAU.EDU>
Sent: Tuesday, September 27, 2005 4:00 PM
Subject: Science "Magic" Demos


> 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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