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[Phys-L] Re: Energy & Projectile Lab

And the second question is: "did you correct to frictional losses?"
Correction for frictional losses is usually made on the basis of the
difference of elevations at which the rolling ball comes to the lower
end of the tube with zero speed.

Ludwik Kowalski
Let the perfect not be the enemy of the good.

On Thursday, Mar 17, 2005, at 16:23 America/New_York, Spagna Jr.,
George wrote:

Dwight asks

-----Original Message-----
From: Dwight K. Souder [mailto:crvhs_dks@CRESTVIEW-RICHLAND.K12.OH.US]
Sent: Thursday, March 17, 2005 3:51 PM

Greetings everyone. I'm looking for suggestions/advice for a lab. We
currently going over potential/kinetic energy and recently covered
idea I have (that I'm certain others had done) was to roll a marble
plastic tube. The marble then would roll across and off of the lab
and hit the floor at a certain spot. Based upon knowing how high the
is from the table, they can calculate the speed of the marble as it
the tube and rolls across the table. Knowing the speed of the marble
height of the lab table, they should be able to figure the range of
marble. To add some fun to it, I also planned on having them place
bulls-eye of where they think it'll land...each ring was worth some

When I've tested the setup, I'm not getting very good results. My
setup was
the following: top of the plastic tube was 60cm from the top of the
table, 90.07cm from the lab table to the floor, and the marble's range
97cm. I figured that it should've landed 147cm from the edge of the
table (about 34% error). I've tried different tube heights and my
would fluctuate (the best being 24% error).

I'm curious if others had done something similar and suggestions for
improving my setup.

Just a thought - did you account for the rolling of the marble? That
will reduce its translational speed because part of KE is tied up in

"Curiosity, like coffee, is an acquired
need. Just a titillation at the beginning,
it becomes with training a raging
passion." -- Nicholas S. Thompson

Dr. George Spagna
Chair, Physics Department
Randolph-Macon College
P.O. Box 5005
Ashland, VA 23005-5505

phone: (804) 752-7344
fax: (804) 752-4724
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