Message-Id: <v01540b2bb0e41aaf45be@[192.174.2.173]>
Date: Thu, 15 Jan 1998 12:04:25 -0800
To: pinhole@exploratorium.edu
From: pauld@exploratorium.edu (Paul Doherty)
Subject: Re: Waves question?
Another way to do marc's experiment is with coiled phone cords, the wave
speed along these cords is fairly slow, and they are nearly indestructible
unlike slinkies. I tie the far end to a light string or monofilament fish
line and stretch the string as far as space allows. The long string gives a
longer time before the second reflected wave comes back.
Think of a triangular upward pulse moving to the right along a string, The
point at the top of the triangle is being pulled down by the two downward
sides of the triangle. When the triangle pulse reaches the end of a string
it is only being pulled down by one side. The length of stretch on that one
side is then doubled, so the pulse gets twice as high still upward at the
end of the string.The pulse then reflects without inverting.
Paul Doherty