Date: Tue, 30 Sep 2003 14:53:37 -0600

Author: Jerry DiMarco

Subject: Re: gravity

Post:

Sometimes information turns up in unexpected places. I wonder where
Acoamerica got that list. The USGS (usgs.gov) is the keeper of such data
in the US. See for example:
http://pubs.usgs.gov/imap/i-2364-h/
If they don't have international data, they probably know where to get it...

Jerry


At 03:31 PM 9/30/2003, you wrote:
>This pdf file has that city, Anthony. Just ignore the instructions...I
>don't know what they're for.
>http://acomamerica.com/docs/LS-100%20Weightless%20Calibration%20P.pdf
>
>Chele
>
>
>Anthony Lapinski wrote:
>
>>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?


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

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 dodds@rice.edu Tue Sep 30 14:16:53 2003
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From: Stanley A Dodds
To: tap-l@listproc.appstate.edu
Subject: Re: Inertia Ball
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OK, this is a classic. There is nothing critical about the apparatus,
so you can make one from whatever is easy to get.

Our set-up uses a disk of lead, left over from something. Two
eyebolts are screwed radially into the edge of the disks at opposite
ends of a diameter. The frame consists of two sturdy lab stands
holding up a cross bar.

A string is looped through one of the eyebolts, around the bar, and
tied into a loop. The weight now hangs from a loop of string. Another
loop is formed through the bottom eyebolt. The "operator" puts a heavy
steel rod (from another lab stand) through the lower loop and strikes
down hard to break the bottom loop. If done quickly the bottom loop
breaks before the lead mass displaces significantly, so the top string
does not break. We usually repeat with a double loop of string through
the bottom eyebolt. For effect, you can put a big pad under the
apparatus "to avoid damaging the table".

As a demo, it is in the same class as pulling a tablecloth out from
under a bunch of dishes. It shows that a=F/m, sort of,
qualitatively. I'm not sure how much students learn, but maybe it
helps them realize that big accelerations require big forces. They
certainly like these demos.

Stan

On Tue, 30 Sep 2003, George M. Caplan wrote:

> Sam writes:
>
> Can you describe the demo?
>
> Thanks,
>
> Sam
> *********
> A large cylindrical mass is supported by a string.
> Another similar string is tied to the bottom of the mass.
> The whole thing is in a "frame".
> The "operator" pulls *with two hands" on a rod tied to the lower string.
>
> George
>
>
From sampere@physics.syr.edu Tue Sep 30 14:18:02 2003
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Date: Tue, 30 Sep 2003 17:00:30 -0400
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George,

I do the demo with 1 kg masses and cotton string, like from a bakery. I
have a 50 year supply of the stuff. Choose your string and masses so
that the string breaks when about 1.5 ~ 2x the mass breaks the string.

So, you found some string and want to try this. Set up some clamps and
rods so you have a secure horizontal bar above the table Tie the string
to the horizontal rod and add mass until the string breaks. Divide this
mass by 2 and that gives you value of one of the single masses. Always
use the same string and this will never fail.

Always use the rod below. Keeping your hands away from the falling mass
is important! Put a board on the table for protecion from the falling mass.

To make this easy, thread some hooks into your mass. Cenco used to sell
large blue balls (ok, take it easy) with the hooks already attached. SW
may still sell them.

If you want to make it, buy some large steel balls from McMaster-Carr or
use a shot put (a girls high school shot is lighter). Drill and tap the
mass and thread in some hooks.

Sam

George M. Caplan wrote:

>Sam writes:
>
>Can you describe the demo?
>
>Thanks,
>
>Sam
>*********
>A large cylindrical mass is supported by a string.
> Another similar string is tied to the bottom of the mass.
>The whole thing is in a "frame".
>The "operator" pulls *with two hands" on a rod tied to the lower string.
>
>George
>
>
From wca1@humboldt.edu Tue Sep 30 14:33:03 2003

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