Re: [Phys-l] Crater Help

["LaMontagne, Bob" <RLAMONT@providence.edu>]

Hi,

This is one of our more popular experiments with our students. We have
found that "Play Sand" for filling children's sandboxes works the most
effectively. We use half inch, one inch, and two inch steel balls
dropped from 0.5, 1.0, 1.5, and 2.0 meters. When plotted on log-log
paper or on Excel we get a surprisingly linear plot with a slope ranging
from 3.75 to 4.25 - which is what is expected for loose sand. The
craters are clearly larger as more massive balls and higher drops are
used. Measure the crater diameter in three different directions and
average to account for asymmetries. Also, use at least 6 inches of sand
in large plastic bins.

Great experiment!

Bob at PC

> -----Original Message-----
> From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
> bounces@carnot.physics.buffalo.edu] On Behalf Of Josh Gates-fac
> Sent: Friday, February 09, 2007 2:17 PM
> To: Forum for Physics Educators
> Subject: [Phys-l] Crater Help
>
> I'm trying to run a lab with some conceptual physics students
(freshmen)
> about crater formation (crater characteristics and their relationship
to
> KE/gPE of the "meteorite"), but am having trouble getting anything
other
> than deeper/less deep craters with heavier/lighter balls.  From the
talk
> on webpages discussing the various incarnations of this experiment, I
am
> also expecting to get some wider/narrower craters.  All of my craters
are
> almost exactly the width of the balls.  I'm using uncompacted flour.
Any
> hints?
> Thanks,
>
> Josh Gates
> Stoneleigh-Burnham School
> Greenfield, MA
>
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