List I keep dinking around with this see saw thing and ran into an interesting tid bit the other day. As a result of the response I got from that proffessor of physics a week or so ago about why the see saw rocks back and forth until it refinds its equilibrium... I decided to try and see what happens when you get a "friction free" pivot placed "exactly" at the see-saws center of gravity, instead of under it. So I took the bearing swivel that comes with the Stanwood kit and bored a hole in a piece of wood so that it would fit snuggly on to this. The stick was roughly 3 mm thick 2 cm wide and 20 cm long. I had to sand a bit off one of the ends to get it to find a near perfect horizontal equilibrium, but once done I got a bit suprised. What happened was this... If I disturbed this horizontal equilibrium just a little... i.e. pull the stick down on one end or the other about 20 degrees and let it go.. then it very slowly finds its way back to horizontal. But if I pull that same end down about 60 degrees or more and then let it go, it finds a new equilibrium in a vertical orientation. Not only that... but if I pull the other end down the same thing happens but in the opposite direction. I have a feeling that whats going on here is that the stick wants to find the closest position of equilibrium where its total mass is balanced and perpendicular to the force pulling at it downwards, gravity. So even in the total absence of friction.... gravity would exert enough force to sooner or later orientate a moving stick thus mounted in one of these positions. Grin... all this to simply be sure of myself on certain leverage issues.... I love it :) I would of course welcome any enlightening comments. Cheers RicB -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway mailto:rbrekne@broadpark.no http://home.broadpark.no/~rbrekne/ricmain.html
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