[Phys-L] Re: Energy & Projectile Lab

[Ludwik Kowalski <kowalskil@MAIL.MONTCLAIR.EDU>]

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
> are
> > currently going over potential/kinetic energy and recently covered
> > idea I have (that I'm certain others had done) was to roll a marble
> down
> > plastic tube.  The marble then would roll across and off of the lab
> table
> > and hit the floor at a certain spot.  Based upon knowing how high the
> tube
> > is from the table, they can calculate the speed of the marble as it
> exits
> > the tube and rolls across the table.  Knowing the speed of the marble
> and
> > height of the lab table, they should be able to figure the range of
> > the
> > 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
> points.
>
> > 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
> 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.
>
>
> 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
> rotation.
>
> ********************************************
>  "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
> e-mail: gspagna@rmc.edu
> http://faculty.rmc.edu/gspagna
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