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Re: CONSERVATION OF ENERGY, work, sound, EM



On Mon, 28 Jul 1997, Thomas L Wayburn wrote:


On Sun, 27 Jul 1997 13:00:10 -0700 (PDT) William Beaty <billb@ESKIMO.COM>
wrote a whole bunch of stuff.

Hi Bill,

I'll have whatever you're taking.

;)

My philosophy: drugs don't cause odd behavior, BRAINS cause odd behavior!

I enjoyed your rap very much. I
think you have confused a lot of things though. Linear sound (as we
studied it in the physics books, viz., Helmholtz, etc.) does not do work.

I guess I wasn't clear enough with my thought experiment. I'm saying that
all work is identical to sound, that if we videotape the world and play
the tape back 1000 times faster, everything will appear as pulses and
vibrations. If we play the tape 1000 times slower, we will see
propagating waves carrying the "work" from muscles, along bones, out along
broom handles, or out to physical objects being lifted (etc.) When we
lift one part of a non-point extended object, the "work" is communicated
to all other parts of the object at the speed of sound in that material,
hence "work" is identical with "sound."

Or, as my unclear thought experiment shows, if we do oscillating work on a
frictional system, and if we then slowly increase the frequency until it
is unquestionably "sound", there is no special frequency where the physics
makes a transition from "work" into "sound". The difference between
"work" performed at 1/2HZ and "sound" performed at 500HZ is only in the
human minds, it is not real. If I scrub the floor with a mop, and push
the mop head back and forth once per second, I perform work upon my end of
the mop handle, but I also broadcast 1hz sound waves down the mop handle.
We live in an entirely acoustics-run world. I find it immensely
entertaining to stagger around with this thought lodged in my head,
forcing me to see sound waves in everything that occurs.

It is lost work. It is almost like turbulence in a fluid. Whatever is
done in one direction is undone in another.

Ah, perhaps you mean that thermal effects are not work, so if I scrub the
floor with a mop, I don't perform work? Yes, the performed work is lost
as a temperature rise, but on my end of the mop handle it certainly is
work.

OK, how about an oscillating system. Suppose I climb to the top of the
playground swings, have someone sit in one swing, then I push them into
increasing motion by pushing and pulling upon the rope of the swing near
the top. I inject energy into the system, I perform work. The "work" is
communicated from my muscles, along bones, to the rope, and down to the
oscillating child. In this case the "work" is not lost, so you must agree
that it still is "work." I point out that this work is "sound". It makes
no difference whether the system is 1cm high and runs at 500HZ, or 3m high
and runs at 1/4HZ.

I also must point out that, as far as my muscles, bones, and the swing
rope is concerned, the physics of the propagating waves is identical to
the physics of the waves moving in the mop above. Whether the work is
lost into heating effects, or is stored in an oscillating system, work is
still performed. (And sound is still generated.) I don't agree that we
can point to the final destination of the propagating waves and, if they
raise a temperature rather than raising an object, say that work was never
performed in the first place.

Electricity IS work when it
crosses our system boundary. But, radio waves are lost work. When you
broadcast it, you lose it; and, you can't get it back.

My point was that electric company "electricity" is not electrons, it is
propagating waves of e-fields and b-fields which surround the wires. In a
radio broadcast system, "radio waves" travel along the wires to the
antenna, and then are coupled into space so that they can leave the
system. If the antenna is replaced by a light bulb, the "radio waves" are
absorbed by the filament and the bulb lights up. But there is no special
frequency where "radio waves" become "electricity". A 60hz generator can
send waves to a (large) antenna or to a light bulb, and if we ignore the
antenna or light bulb and look ONLY at the waves around the connecting
wires, there is absolutely no difference between the waves travelling to
the antenna and the waves travelling to the light bulb. If we raise the
frequency to 100mhz, the wavelength changes, but nothing else does. The
difference between "radio waves" and "electricity" is a difference created
only in human minds, and is not something out in the real world. Hence,
our civilization is powered by radio. And hence, one can lodge this
"vision" in one's mind, and stagger around the world seeing everything
powered by radio waves. (Change the old Beatles lyrics from "you can be
Jesus" to "you can be Tesla!")

(Or less weird an idea: our civilization is powered by propagating
electromagnetic energy, which at low frequency we call "electricity" and
at high frequency we call "radio waves").

Forget about
what the TV stations say during ball games. When they broadcast it,
they gave it up.

Whether the "work" is lost or not makes no difference to what happens
around the wires. If I place a dish antenna around the TV broadcast
antenna, focus the waves onto a second dish and antenna, rectify the
received energy, and power a DC motor, how does this change what happens
in the wires at the TV *transmitter?* I say there is no change, and work
was performed in both cases.

Mopping the floor ain't work except in so far as dirt
is actually moved, but not the rubbing.

When I apply a force to my end of a mop handle, I perform no work? But if
I use the mop handle to lift an object for example, then I do perform
work? I disagree. At the place where my hands touch the handle, there is
no difference between scrubbing the floor and lifting a mass, so I must
say that I perform work. Where the energy goes afterwards is a separate
issue. My muscles, bones, flesh, and the mop handle don't know that there
is (or is not) an irreversable system at the other end. It feels like
work, and at the microscopic level it is work. I would agree that the work
is wasted once it arrives at the far end of the mop handle. But this
doesn't control what happens at my end of the rod. Muscles still perform
work.

Mind if I forward this to phys-L? It might get others going on the topic.

......................uuuu / oo \ uuuu........,.............................
William Beaty voice:206-781-3320 bbs:206-789-0775 cserv:71241,3623
EE/Programmer/Science exhibit designer http://www.eskimo.com/~billb/
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