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From: ecn-ec:ecn-pc:ecn-ed:vu@pur-ee.UUCP
Newsgroups: net.physics
Subject: Re: long lever - (nf)
Message-ID: <143@ecn-ed.UUCP>
Date: Sun, 7-Aug-83 17:35:51 EDT
Article-I.D.: ecn-ed.143
Posted: Sun Aug  7 17:35:51 1983
Date-Received: Mon, 8-Aug-83 10:59:31 EDT
References: uiucdcs.2520
Lines: 13


	The sln by uiuccsb!krueger sounds good to me, but only that
`forces holding the lever travel no faster than ...' does not make sense.
The molecular forces inside the bar do not travel from A to B but in an
arc about B. Instead, what is traveling here is the impulse made by A to
swing the lever: it is then a form of wave propagation. And mechanical
wave (A's impulse) on a solid (lever) propagates much slower than E-M waves.
Thus, if B relies *only* on movement of lever to signal the laser, then A
will have to wait much more than 20 years before receiving it.

				Hao-Nhien Vu.
				pur-ee!vu
	or(better)		pur-ee!norris