Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: Notesfiles $Revision: 1.7.0.10 $; site uiucdcs Path: utzoo!watmath!clyde!cbosgd!ihnp4!inuxc!pur-ee!uiucdcs!mcewan From: mcewan@uiucdcs.CS.UIUC.EDU Newsgroups: net.physics Subject: Re: Monkey business Message-ID: <24400048@uiucdcs> Date: Tue, 12-Nov-85 16:19:00 EST Article-I.D.: uiucdcs.24400048 Posted: Tue Nov 12 16:19:00 1985 Date-Received: Thu, 14-Nov-85 00:46:32 EST References: <2748@brl-tgr.ARPA> Lines: 39 Nf-ID: #R:brl-tgr.ARPA:2748:uiucdcs:24400048:000:1650 Nf-From: uiucdcs.CS.UIUC.EDU!mcewan Nov 12 15:19:00 1985 > Having allowed sufficient time for readers to > ponder system instability, now I wish to observe > that there is a finite characteristic time for > the evolution of the instability (on the order > of sqrt(2*h/g), where h is the distance to the > pulley and g is as usual the gravitational > acceleration; more if the angular momentum of > the pulley is substantial), so if the monkey > climbs sufficiently fast he can be assured of > reaching the top before the counterweight does. > > For sufficiently fast climbing rate, the > position of the counterweight at the end of > the monkey's climb is dependent on variables > such as rope density and moment of inertia of > the pulley. If these are appreciable, the > counterweight will remain at its initial > position (except to the extent that the system > instability has procgressed). > > If the monkey climbs much more slowly than the > characteristic time for system collapse, then > the experimental outcome is ill-determined. > > The in-between behavior could be interesting.. Well, I pondered, and came to the conclusion that you can't read very well. Re-read the statement of the problem - the system is NOT unstable, the angular momentum of the pulley, the density of the rope, and the moment of intertia of the pulley are all ZERO. The key words are: MASSLESS rope, MASSLESS, FRICTIONLESS pulley. Scott McEwan {ihnp4,pur-ee}!uiucdcs!mcewan "A flash in front of my eyes ... I blink ... open my eyes to ... discover I am a dog in a pickup truck full of garbage ... no one but me sees the lid blow off the can ... it's 14 miles to the dump ... this is ... at last ... heaven."