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From: mcgeer@kim.berkeley.edu
Newsgroups: net.physics
Subject: Monkey problem
Message-ID: <716@sri-arpa.ARPA>
Date: Thu, 31-Oct-85 12:27:33 EST
Article-I.D.: sri-arpa.716
Posted: Thu Oct 31 12:27:33 1985
Date-Received: Mon, 4-Nov-85 02:13:45 EST
Lines: 24

From:  mcgeer@kim.berkeley.edu (Rick McGeer)


>Date: 30 Oct 85 13:31:01 EST (Wednesday)
>From: MJackson.Wbst@Xerox.ARPA
>In-Reply-To: <8510300838.AA18569@sri-unix.ARPA>
>Cc: MJackson.Wbst@Xerox.ARPA, Physics@SRI-Unix.ARPA
>
>Simple answers to these questions quickly get confounded in the
>ambiguity of "The Monkey. . .starts climbing the Rope."  It is simplest
>if we take this to mean that the Monkey exerts a force Fm on the Rope
>which exceeds MG (where M is n Kg and G is the acceleration of gravity).
>Then by considering tension in the Rope it is clear that:
>
>If the Rope is massless and the Pulley is frictionless and massless then
>the Monkey and the Weight both accelerate upward at the same rate A =
>Fm/M - G.

Not quite correct.  Since both the monkey and the rope weigh M, the total
mass on the rope is 2M, hence Fm = 2M(G + A) hence A = Fm/2M - G.

Picky, picky, picky.

						-- Rick.