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My e-mail test - Please Ignore



This message is being resent. It has now been sent 2 times. I'm trying
to get to the bottom of some e-mail problems. There is no relevent
content in this message for Phys-L participants. The message below got
garbled when sent earlier. I have changed some of my e-mail parameters.
Is this message coming back to me garbled, or have I omproved things?

In response to John Mallinckrodt... I didn't necessarily want to imply
that "no dissipation of energy" is 100% possible. But I was saying this
in the same spirit that we say it when we study "elastic collisions" in
general-physics class. We still do that don't we? I.e. we pretend it
is possible to have an elastic collision, which is defined as one in
which kinetic energy is conserved, even though we know the deformation
of the bodies during impact will result in some amount of thermal
energy.

Is that where we differ, John? Or are you talking about something else
I am not picking up on?

If you are indeed saying that macroscopic bodies can't have 100% elastic
interactions, then I agree. But I think we often do "back of the
envelope calculations" in which we assume that they nearly do.

Also, what assumptions are being made about I for this wheel. I was
assuming a disk with I = 0.5mr^2. In this case I get v_f =
r*w_0/sqrt(3) if there is absolutely no dissipation, and I get
v_f=r*w_0/sqrt(5) if there is dissipation due to "slippage."

Note that there is no disagreement that mu does not appear, and that the
final velocity is r*w_0 times some factor. We just aren't agreeing on
what that factor is. I'm not getting r in this factor, I assume because
of my assumption for I. But also, is there a dimension problem in the
results that John gave? How do the units work out on the factor that
multiplies r*w_o? Doesn't that need to be dimensionless?


Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton College
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.