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Yes, but what is the physical mechanism whereby the
cancelling, reflected
wave is generated?
Perhaps something like: When an upward going
vertical pulse on a rope
encounters a rigid wall termination, the last rope
segment exerts an upward
force on the wall. The wall responds by exerting a
downward pull on the
rope segment (by N3), thus starting a downward going
vertical pulse on the
rope.
The mathematical argument shows how WE KNOW that
some such mechanism must be
acting; only the physics (Newton's laws in the rope
case) can identify that
mechanism.
The theorist is often completely satisfied with only
the mathematical
answer; the unwashed student has yet not acquired
sufficiently naive faith
in mathematical models; he still requires the
confirmation of a physical
mechanism.
Bob
Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
www.velocity.net/~trebor
----- Original Message -----
From: "Jack Uretsky" <jlu@HEP.ANL.GOV>
To: <PHYS-L@lists.nau.edu>
Sent: Tuesday, April 25, 2000 8:46 PM
Subject: Re: Wave phase reversal on reflection
I thought that cancellation of the transmittedwave is about as physical
as one can get.scientist; I was the same, and
Jack
Adam was by constitution and proclivity a
we loved to call ourselves by that greatname...Our first memorable
scientific discovery was the law that water andlike fluids run downhill,
not up.from Eve's Autobiography>
Mark Twain, <Extract
this query concern
On Tue, 25 Apr 2000, Bob Sciamanda wrote:
It is interesting that all of the responses to
mathematicalarguments based upon the need to satisfy certain
requirements
that the student askingof the wave function. It is my experience
such
MECHANISM behind the behaviorquestions is seeking a concrete PHYSICAL
in
question will be differentquestion. The answer to this aspect of the
for
acoustical vs E/M ).each different kind of wave phenomenon ( eg:
problem - we should try to
This is a common pedagogical communication
get
queries (withoutmore concretely physical in addressing student
prejudice
student has not yet becometo the guidance of mathematical models). The
model thinking to besufficiently jaded into abstract, mathematical
mechanisms of his concrete,persuaded that they EXPLAIN the physical
projected past the boundaryconceptual questions.
Bob
Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor
----- Original Message -----
From: "Jack Uretsky" <jlu@HEP.ANL.GOV>
To: <PHYS-L@lists.nau.edu>
Sent: Tuesday, April 25, 2000 2:34 PM
Subject: Re: Wave phase reversal on reflection
Remove the boundary. The reflected wave
region beyond themust exactly cancel the incident wave in the
boundary.
scientist; I was the same,Regards,
Jack
Adam was by constitution and proclivity a
and
name...Our first memorablewe loved to call ourselves by that great
and like fluids runscientific discovery was the law that water
from Eve'sdownhill,
not up.
Mark Twain, <Extract
Autobiography>
explanatiion for the phase
On Mon, 24 Apr 2000, SSHS KPHOX wrote:
My colleague asked if there were a good
boundary where the new speedreversal when a wave reflects from a
will
don't have one for her.be
less and not when going from slow to fast. I
Can
anyone help?
Ken Fox
AP/IB Physics Teacher
Smoky Hill High School, CO