Science answer: Gravity applied to the see saw, gravity applied to the weight, force/counter force etc. Philosophical answer: because Brian ----- Original Message ----- From: "Richard Brekne" <Richard.Brekne@grieg.uib.no> To: "PTG" <pianotech@ptg.org> Sent: Friday, February 28, 2003 9:44 PM Subject: A "simple" see saw question List... In my pursuit of a better understanding of the concept of Balance Weight and in general of grand action leverage ran into this seemingly simple question, and posed it to several folks around the world. Here is a response I found particularilly interesting. From Michael Fowler wrote Commonwealth Professor Department of Physics University of Virginia > Richard Brekne asks: > >Given a see saw with say 10 kilos weight 1 meter on each side of the > >fulcrum. If you then push down on one end and let go the see saw will > >rock back and forth until slowly it refinds its state of equilibruim. > >Why exactly does this happen ? I understand that friction is the thing > >that brings it back into equilibruim, but why the rotational movement to > >begin with exactly ? > > >Richard Brekne > > Perhaps you think I know something about seesaws because of my notes at > http://www.phys.virginia.edu/classes/581/RotationalMotion.html > > I agree with you that IF a seesaw has the axle right through the center of > gravity of the plank, there's no reason why it should go back to a > horizontal position. But I've seen seesaws in playgrounds where it > definitely does go back to horizontal -- I believe these must be built with > the center of gravity of the plank slightly BELOW the axle, so the stable > position is horizontal. I also seem to remember some very fancy seesaws > with hydraulic dampers -- obviously, these could be adjusted to keep the > rest position horizontal. So... either he misunderstood the question... or I've some more head scratching to do. :) whatelse is new eh ? -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway mailto:rbrekne@broadpark.no http://home.broadpark.no/~rbrekne/ricmain.html _______________________________________________ pianotech list info: https://www.moypiano.com/resources/#archives
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