Date: Fri, 26 Sep 2003 12:20:10 -0400

Author: Stephen Bannasch

Subject: Re: Awesome EM induction demo!

Post:

At 8:54 AM -0500 9/26/03, Paul Nord wrote:
>yes.
>
>The conductivity increases a lot with thickness. A thin-walled copper pipe that you might use for plumbing will show no drag when you drop a magnet through it.
>

Not my experience. When I drop a 0.7" spherical neodymium magnet down through a two foot section of 1" copper standard plumbing pipe the magnet takes about 2s to transit the pipe. It is the strangest thing to watch from above.

--

-- Stephen Bannasch
Director of Technology, Concord Consortium
http://www.concord.org mailto:stephen@concord.org
From wwsee@ou.edu Fri Sep 26 09:41:14 2003
Date: Fri, 26 Sep 2003 11:24:26 -0500
From: Bill See
Subject: Quthestions regarding the RubensTube aka (Flame Pipe)
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I've been asked to build a Rubens tube and after looking at various
designs I have some questions:

1. Would a narrower tube work as well, say 2"dia? Why?

2. What would the minimum useful length be? Why?

3. Is there an optimum distance between the holes? Why?

4.How important is the rubber dam? I have seen them on the speaker end,
the opposite end,
and none at all. Why?

My mother said I drove her crazy with "why, why, why?"
Thanks in advance for all the help.

Bill See
O.U. Physics Department
Norman, OK
wwsee@ou.edu

From edwardsabol@hotmail.com Fri Sep 26 09:46:27 2003
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From: "Edward Sabol"
To: tap-l@listproc.appstate.edu
Subject: Re: Newton's Third Law
Date: Fri, 26 Sep 2003 16:29:47 +0000
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Nice which spring scales to you use (supplier)

>From: KBouff@aol.com
>Reply-To: tap-l@listproc.appstate.edu
>To: tap-l@listproc.appstate.edu
>Subject: Re: Newton's Third Law
>Date: Fri, 26 Sep 2003 10:45:49 EDT
>
>When I teach the third law, I phrase it a little differently, "When one
>object exerts a force on another, the forces are equal and opposite, and
>the forces
>act on different objects. I have had too many teacher who only teach
>"action
>and reaction" so the students could never apply it to the car and truck
>problem. They seem to forget the second part which makes the truck and car
>collision
>so hard for them to swallow. I have two students sitting on rolling chairs,
>one with noticibly more mass than the other. They each hold a ribbon that
>is
>knotted in the middle (a spring scale is inserted on each side of the
>kinot. I
>ask the students to predict what the spring scales will read. Then I have
>them both pull. The readings on the spring scales will be equal but both
>objects
>accelerate toward each other, although the more massive student doesn't
>accelerate as much. This visibly shows the effect of the same (but opposite
>force),
>acting on two different masses. This demo builds on their knowledge of the
>second law.
> Karen

_________________________________________________________________
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From dwilley+@pitt.edu Fri Sep 26 09:48:17 2003
Date: Fri, 26 Sep 2003 12:31:09 -0400
From: David Willey
Subject: Re: Awesome EM induction demo!
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Yes the liquid nitrogen had quit boiling (BTW does anyone know what
causes that last rush of boiling that occurs just before the boiling stops?)

William Beaty wrote:

>On Thu, 25 Sep 2003, David Willey wrote:
>
>
>
>>I only got a 7 inch drop, any more and the magnet hit the copper.
>>
>>
>
>Maybe it's not cooled all the way. Did the nitrogen poured on top of the
>copper still boil?
>
>
>
>
>
>
From rueckner@fas.harvard.edu Fri Sep 26 10:33:26 2003
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