Re: angular momentum transfer?

[Bernard Cleyet <anngeorg@PACBELL.NET>]

After reading (skimming) the replies so far, I agree w/ the later
replies that your memory may be defective, not unheard of here.

I think what you want to demonstrate is conservation of momentum in a
small closed system.

I've described one of my more favoured demos before, and will now bore
the longer time members.

Suspend a large pocket watch on a rigid card (any low mass platform)
using three threads tied to a single one which is hung from a hook.
fasten w/ tacky wax a small mirror on the watch; aim a laser at the
mirror so that it then falls on a far wall.  i.e. a light lever.  This
will show the watch moving opposite to the motion of the balance wheel
*, roughly showing the conservation of momentum.

* One may remove the back and place the mirror on the platform, so one
may verify (using, say a TV camera) that there is counter rotation.
With the aid of a watchmaker one may determine the mass, etc. and put
some numbers in the mix.

bc

p.s. on a larger scale:  sit on a piano stool and rotate a lead weighted
bicycle wheel.

Colin Quinney wrote:

> Hello.
>
> I joined yesterday. I am searching for some information. I am a fairly new
> student of physics, now retired, and I am presently searching for a
> reference to a classroom demo that shows two wheels on a short axle, where
> one wheel with lead (Pb) rim is spun up-  and another wheel close by (on
> the same axle) responds to the momentum change of the first wheel with a
> small reverse rotation. I wish to replicate this so that I may study the
> phenomena. Neither my text books nor Google however give a reference or
> shows this demonstration. I'm confident however that a demo of this sort is
> out there somewhere since a retired physics professor originally told me
> about it. If anyone could please advise or give a science book reference or
> to a correct Google search term, I would be most appreciative. Thanks.
>
> Best Regards,
> Colin