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[Phys-L] Re: Energy & Projectile Lab

Even accounting for the rotational KE, the difference seems too high.
Does the marble run along a groove in the tube (so that the radius of
rotation is smaller than the radius of the marble)? Does the edge of
the table have a lip to it? Is everything placed on a pad of some kind
that might be absorbing the energy when the marble bounces on the table?
Could the marble be sliding along the tube? Or, am I missing something
more obvious?

Robert Cohen; 570-422-3428;
East Stroudsburg University; E. Stroudsburg, PA 18301

-----Original Message-----
From: Forum for Physics Educators
[] On Behalf Of Daniel Crowe
Sent: Thursday, March 17, 2005 4:38 PM

The range would be 1.47 m if the marble did not rotate and
did not lose any mechanical energy. The range would be 1.24
m if the marble rolls without slipping but does not lose any
mechanical energy.

A relative error of -24% from 1.47 m is 1.12 m, which has a
relative error of -10% from 1.24 m. A range of 0.97 m has a
relative error of -22% from 1.24 m.

On Thu, 17 Mar 2005 15:51:22 -0500, Dwight K. Souder
<crvhs_dks@CRESTVIEW- RICHLAND.K12.OH.US> wrote:

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

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