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Re: arons and dry ice

Bernard, what is "the little glassier tramp"?

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From: Bernard Cleyet
Reply To: phys-l@lists.nau.edu: Forum for Physics Educators
Sent: Wednesday, October 9, 2002 1:49 AM
To: PHYS-L@lists.nau.edu
Subject: Re: arons and dry ice

I've purchased dry ice for a diffusion cloud chamber and it's not
inexpensive. If I
remember correctly, a 10 inch square two inch thick block weighs ~10# and
is about
$5. You could try putting a steel or lead block on a square. I suspect
it'll
support 20#, then you'll have 30#. Enuff for your demo.? If necessary
use two
blocks. Your local glassier may have a large scrap plate from a store
front he'll
donate. Your old slate lab bench, as Cliff suggests, may do.

Of course your students could generate the glass à la the little glassier
tramp.

bc

Manny, Moe, and Jack had no position on plate glass

Justin Parke wrote:

In a message dated 10/8/2002 7:43:38 PM Eastern Daylight Time,
cparker@CHARTER.NET writes:

No need for a 50 pound chuck of dry ice or glass. Any size chuck will
do.
Something about the size of your computer mouse works well. Place it
on top
of a demonstration table or tile floor if that's all you have. Make
sure
the surface is as clean as you can get it. Let the chuck sit for a
few
minutes until the bottom surface of the ice becomes flat. Then just
give it
a scoot. Extension - take a wet paper towel and wipe some moisture on
the
table top then slide the dry ice over the moisture. Cool smoke!
Extension
2 - put a chuck of dry ice on an aluminum chalk tray or other metal
surface.
Press down with a stick or while wearing a glove. It will screech and
holler like you wouldn't believe. Have fun.

Cliff Parker


I think one of the benefits of a large chunk is the opportunity for the
students to interact with a lot of inertia. Arons was citing the
"preconception" that a force is to be equated strictly with an impulse,
but
an impulse will be insufficient to stop a 50 lb chunk and the students
will
be forced (no pun intended) to push for a longer period of time. Then
they
realize that a force can be exerted over a period of time, and that when
the
force is no longer being exerted, it *no longer has an effect*. A small
chunk may reinforce their preconception, but OTOH it may be all I can
reasonably do.

Thanks for the feedback

Justin

This posting is the position of the writer, not that of SUNY-BSC, NAU or
the AAPT.

This posting is the position of the writer, not that of SUNY-BSC, NAU or
the AAPT.




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This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.