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From: wasser@mosaic.dec.com.UUCP
Newsgroups: sci.physics
Subject: Acceleration vs. Gravity
Message-ID: <6108@decwrl.DEC.COM>
Date: Mon, 27-Oct-86 09:25:05 EST
Article-I.D.: decwrl.6108
Posted: Mon Oct 27 09:25:05 1986
Date-Received: Mon, 27-Oct-86 22:29:53 EST
Sender: daemon@decwrl.DEC.COM
Organization: Digital Equipment Corporation
Lines: 30

>  o  Given the old "accellerating-elevator-in-space" experiment,
>     how can one within the elevator tell the whether he is
>     accelerating or under the influence of gravity?

	Two ways to tell if your elevator is just sitting on a big mass:

	1) The acceleration is stronger at the bottom of the
	elevator because the bottom is closer to the center of
	gravity.

	2) Two plumb lines will converge slightly because both strings 
	point toward the center	of gravity of the mass.  The strings
	would hang parallel under acceleration in space.
 
	Warning: Experiment 2 can probably be fooled by appropriately
	shaping the large mass.
 
			-John A. Wasser
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P.S.  Design of experiments to test for properties 1 and 2 are left as
	an exercise for the reader!