Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!ROVER.RI.CMU.EDU!Hans.Moravec
From: Hans.Moravec@ROVER.RI.CMU.EDU
Newsgroups: sci.space
Subject: Faster than sound
Message-ID: <8902131948.AA06208@angband.s1.gov>
Date: 13 Feb 89 19:45:38 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 9


As Arthur Clarke has pointed out in several books, the crack
of a whip is a sonic boom caused by the tip exceeding the
speed of sound. As the momentum in the heavy part of the
whip near the handle moves in a wave towards the lighter
tip, the velocity increases, until it exceeds that of sound,
and *CRACK*.  The taper of the whip serves to incrementally
match the high impedance of one end with the low impedance
at the other.