A "simple" see saw question

[Richard Brekne]

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