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Re: [Phys-l] Crater Help



Greetings!

I do this lab as well with play sand in deep plastic bins. We the do a
log plot to find the relationship between crater diameter and energy, d
= a E^n, where a is a constant. n, for careful students, comes out quite
close to 0.25. See the excellent paper "Crater Formation inthe
Laboratory: An Introductory Experiment in Error Analysis," AJP 66 (2)
141-143 (1998), by Joe Amato.

Good cratering!

david


David Ward
Professor of Physics
UNU# 3160
Dept. of Physics
Union University
1050 Union University Drive
Jackson, TN 38305-3697
office (731)661-5241
FAX (731)661-5175
dward@uu.edu

"LaMontagne, Bob" <RLAMONT@providence.edu> 02/09/07 1:53 PM >>>
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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