Re: vibration vs. oscillation

[Todd Pedlar <pedlto01@LUTHER.EDU>]

At 10:59 AM 6/25/2004, Carl E. Mungan wrote:
> >2. A particle cannot rotate or vibrate; it can only translate.
>
> Yes, this follows from your previous sentence. I would add that
> rotational and vibrational energies are therefore forms of internal
> energy--they are relative to the COM--in contrast to the bulk
> translational energy.

A quibble on this statement, Carl.  Rotational energy is definitely not
internal.
Just as translational kinetic energy is not internal, because it is a BULK
motion,
so is rotational kinetic energy.  All parts of the object have the same angular
velocity \omega.  Internal energies must involve motion of constituents
relative
to other constituents, and can never involve common motion of the bulk body,
as both translational and rotational motions do.

Todd


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Todd K. Pedlar                   Assistant Professor of Physics
pedlto01@luther.edu          Luther College, Decorah, IA
                                         http://academic.luther.edu/~pedlto01/

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Ludwig Boltzmann, who spent much of his life studying statistical
mechanics, died in 1906, by his own hand. Paul Ehrenfest, carrying on the
work, died similarly in 1933. Now it is our turn to study statistical
mechanics. Perhaps it will be wise to approach the subject cautiously.

                                        -- David L. Goodstein, States of
Matter

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