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Re: physics of bouncing



Title: Re: physics of bouncing
Dear colleagues,
I apologize for entering this discussion in the middle, without having carefully followed what went on before (too many duties and chores to follow phys-l as carefully as it deserves...). However, a recent message by John Denker, answering a previous inquiry, reads:
==============================================================
>After any real collision I do in my lab some of the energy is in the form
>of thermal energy,

OK.

>This is quite imperceptible to my students (other than the fact that the
>objects involved are going slower).

OK.

>  How do I demonstrate that the energy still exists in a different form
> (most intro. students are satisfied with a qualitative demo) ?

Good question.  See below.
===============================================================
Allow me to turn your attention to a short Physics Teacher article of mine:

Elastic and Inelastic Collisions: A Model. (or: What happens to the Kinetic Energy?)
Uri Ganiel
The Physics Teacher, 30, 18-19 (1992).

I describe there a model which explains qualitatively what happens during inelastic collisions. The model has been adopted by some textbook writers (e.g. Lea and Burke, in their new (1998) "Physics, The Nature of Things", p. 345), and has also been used for some PER research at The Ohio State University (Xueli Zou, student of Allan van Heuvelen, now at Chico State in CA). We use it regularly during in-service courses with our school teachers, and it often brings about that "WOW" we like to get...

Uri





 
--
Uri Ganiel, Ph.D.
The Rudy Bruner Professor of Science Teaching
Head, Department of Science Teaching
The Weizmann Institute of Science
Rehovot 76100, ISRAEL

Phone: 972-8-9343894
FAX:    972-8-9344115
E-mail: uri.ganiel@weizmann.ac.il