From: Ron Kean (ronkean@juno.com)
Date: Thu Jul 15 1999 - 10:07:54 MDT
On Thu, 15 Jul 1999 13:10:51 +0100 Rob Harris Cen-IT
<Rob.Harris@bournemouth.gov.uk> writes:
>
>So, the name of the wave comes from the source of its energy - in
>this case
>gravity. Not, as I thought before, the medium in which the wave
>exists......
>Is this correct?
>BTW - cheers for the fine explanation !
>
>Rob.
>
>
I don't say that waves _must_ be named after the force involved (or one
of them) rather than the medium of propagation. In the case of 'gravity
waves' on the surface of water, that is just what is established
terminology. And gravity is not the only force involved with those
waves. Momentum, inertia, kinetic energy, surface tension, and viscosity
would also be required to characterize them. There is nothing
fundamentally wrong with naming a wave after the medium in which it
propagates. 'Electromagnetic waves' could be called 'ether waves'
without harm (sidestepping the question of whether there even is an
ether). In some contexts it could be useful to name waves after their
media.
We mentioned two kinds of 'water waves': gravity waves on the surface of
deep water, and acoustic waves in bulk pressurized water. There may be
yet another kind of 'water wave'. If a sheet of water is flowing down a
sloped, randomly rough surface, wavelets form and travel along down.
This happens even if the roughness of the surface is orders of magnitude
less than the depth of the sheet of water. This phenomenon can sometimes
be seen on a sloping piece of asphalt pavement during a heavy rain, or
even on a sloped piece of glass. Could we call those waves 'water
avalanche waves'? When the big mirror of the Hubble Space Telescope
received its final cleaning, distilled water was run across the surface.
The criterion for knowing when the cleaning was done was when the
wavelets stopped forming and the sheet of water became smooth.
(cc to K. Lynch, physics expert. If I make an error, he will detect it.)
Ron Kean
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