Date: Tue, 30 Sep 2003 12:05:37 -0600

Author: Jerry DiMarco

Subject: RE: Van de Graaff

Post:



At 10:54 AM 9/26/2003, you wrote:

...But the VDG still does not
generate much charge - and as it stays on for a

couple minutes the charge decreases - so it might be leaking
somewhere? 

I replaced the disintegrated cloth on the bottom roller with what I think
is

an acrylic/polyester cloth. I think the two rollers need to be
different

materials - hence the cloth, is that right?  What should the cloth
be, or do

I even need it?


     The webpage below has a triboelectric series
list:
http://www.amasci.com/emotor/tribo.txt

Polyurethane and polyester are pretty close together in the series. 
But maybe more importantly, the polyurethane belt is below the polyester
pulley on the list.  This means the other pulley would have to be
made of a material at the bottom of the list, which is also not far
removed from the polyurethane.  If your other pulley is made of a
material at the top of the list, I'm surprised it works at
all...   


 What is the max distance that
the combs can be from the

roller? 


     According to a VDG manual, the combs should be
within 1/8" of the belt...


I have an older Cenco VDG - about
26 cm sphere and column about 56 cm high.

I should be able to get sparks longer than 10 cm, shouldn't I?


     Under ideal conditions maybe.  10 cm is
what I get under normal conditions...


                                                                Jerry


Suggestions? 


Thanks,


Paul Hezel

Physics Lab Manager

Seattle Univ





<><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

                                                                        

 Jerry DiMarco

 Manager of Lecture Demonstrations and Instructional
Labs

 Montana State Univ., Physics
Dept.                                             

 Bozeman, MT



Our Motto: "There's a demo in there somewhere."

From rtarara@saintmarys.edu Tue Sep 30 11:24:13 2003
Date: Tue, 30 Sep 2003 12:44:05 -0500
From: Rick Tarara
Subject: The Day the Universe Changed video
To: tap-l@appstate.edu
Message-id: <013c01c3877a$714a4b00$96503593@RickTarara>
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I'm trying to find a source of James Burke's 'The Day the Universe Changed'
videos--specifically just one episode 'Infinitely Reasonable'. So far, I
can only come up with www.buyindies.com where they want $800 for the whole
series. I have a request in to see if they would sell a single episode.
What I would like to ask here is if:

1) anyone knows of another source. Ambrose Publishing which now sells
DVD versions of the first Connections series doesn't have it.

2) anyone has an old set that would be willing to sell.

3) anyone with a set who would be willing to dub the one episode for me.
(will pay for tape and shipping)

Thanks,

Rick Tarara

*********************************************************
Richard W. Tarara
Professor of Physics
Saint Mary's College
Notre Dame, Indiana
rtarara@saintmarys.edu
********************************************************
Free Physics Educational Software (Win & Mac)
www.saintmarys.edu/~rtarara/software.html
Energy 2100--class project
www.saintmarys.edu/~rtarara/ENERGY_PROJECT/ENERGY2100.htm
********************************************************


From gcaplan@wellesley.edu Tue Sep 30 11:39:43 2003
Message-id:
Date: Tue, 30 Sep 2003 14:23:20 -0400
Subject: Inertia Ball Device
To: tap-l@listproc.appstate.edu
From: "George M. Caplan"
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In The Video Encyclopedia of Physics Disc 2, Chap. 5, Demo 02-13 is the
“Inertia Ball”.
I would like to know:

A. Is the device shown in that demo commercially available? If so,
where can I get one?
B. Otherwise, might someone know who built the one in the vide and
whether I might
be able to get drawings to make my own?


From anthony_lapinski@pds.org Tue Sep 30 11:48:57 2003
Message-id:
Date: Tue, 30 Sep 2003 14:36:40 -0400
Subject: gravity
To: tap-l@listproc.appstate.edu
From: "Anthony Lapinski"
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I'm trying to find a "simple" listing of the local gravity in worldwide
cities, specifically Oslo, Norway. I've searched the net, but only came up
with gravity tables of longitude and elevation for the US (no specific
cities). A few textbooks list some cities. I am trying to compile a list
of cities around the world to compare ranges for projectiles (Olympic
events) in my class. Can anybody help?
From sampere@physics.syr.edu Tue Sep 30 12:06:17 2003
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Date: Tue, 30 Sep 2003 14:49:43 -0400
From: sampere
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To: tap-l@listproc.appstate.edu
Subject: Re: Inertia Ball Device
References:
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Can you describe the demo?

Thanks,

Sam

George M. Caplan wrote:

>In The Video Encyclopedia of Physics Disc 2, Chap. 5, Demo 02-13 is the
>“Inertia Ball”.
>I would like to know:
>
> A. Is the device shown in that demo commercially available? If so,
>where can I get one?
> B. Otherwise, might someone know who built the one in the vide and
>whether I might
> be able to get drawings to make my own?
>
>
>
>
From gkarshner@stmarytx.edu Tue Sep 30 12:15:58 2003

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