Re: Arons and Dry Ice

[Bernard Cleyet <anngeorg@PACBELL.NET>]

It just occurred that wet ice will probably work quite well on a flat hard surface.

Useful site (gives plots of coefficients as a function of speed, temperature, etc.)

http://www_hockey.tripod.com/

Ice source here may be unusual (for icing ag. trucks); it's very inexpensive:  ~ $5 /
300 # min size (weight). with min. order of ~$13!

check:   Coefficient ~ 0.02 (speed > ~ 0.2 m/s)    So if one applies 10# to a 50#
block 9# is available to accelerate the block (~ 1.6 slug ?) at ~ 5.6 ft/s^2.
Practical for about two seconds.

bc whose mind's eye sees a student pushing with a force of 30# (net 24#) a 300# block
down the hall accelerating at ~ 2.7 ft/s^2.  He stops after two seconds.  The block
stops about ten seconds later and 29 feet further down the hall.

Richard Hake wrote:

> Please excuse this cross-posting to discussion lists with archives at:
>
> Phys-L <http://lists.nau.edu/archives/phys-l.html>,
> PhysLrnR <http://listserv.boisestate.edu/archives/physlrnr.html>,
> Physhare <http://lists.psu.edu/archives/physhare.html>,
> AP-Physics <http://lyris.ets.org/cgi-bin/lyris.pl?enter=ap-physics>.
>
> In his Phys-L post of 8 Oct 2002 19:33:55-0400 titled "Arons and Dry Ice,"
> Justin Park wrote (slightly edited):
>
> "I read in Arons [sorry don't have the specific reference. . .(it's
> Arons 1990). . .] earlier today the section on introducing Newton's
> laws and specifically the concept of inertia and the effects of
> forces on a body's motion.  He recommends a 50-lb piece of dry ice on
> a sheet of glass. (!) Has anyone done this?  How big is the sheet of
> glass?  How big is 50 lbs of dry ice?"
>
> Has anyone done this? YES! The Arons
> 50-lb-dry-ice-floating-on-glass-method of getting Newton's First Law

cut

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