[net.space] Rotational Inertia

@S1-A.ARPA,@MIT-MC.ARPA:BIESEL@RUTGERS.ARPA (07/08/85)

From: BIESEL@RUTGERS.ARPA


I've been watching the comments concerning ways to overcome the gyroscopic
inertia problem with the OMNIMAX cameras with growing disbelief. The 'fix'
seems to consist of a second counterrotating mass whose angular momentum
is matched by various means to that of the filmreel. It won't work, of course.
Adding a second rotating mass, counterrotating, at right angles, or
whatever will simply *ADD* to the problem by creating more angular
momentum. You might as well try to 'cancel' some mass by adding some
mass in another place; it just doesn't work that way.
-------

@S1-A.ARPA,@MIT-MC.ARPA:jrv@mitre-bedford (07/10/85)

From: jrv@Mitre-Bedford


> I've been watching the comments concerning ways to overcome the gyroscopic
> inertia problem with the OMNIMAX cameras with growing disbelief. The 'fix'
> seems to consist of a second counterrotating mass whose angular momentum
> is matched by various means to that of the filmreel. It won't work, of course.
> Adding a second rotating mass, counterrotating, at right angles, or
> whatever will simply *ADD* to the problem by creating more angular
> momentum. You might as well try to 'cancel' some mass by adding some
> mass in another place; it just doesn't work that way.

Of course it works that way.  The angular momentum of a collection of
masses is a vector sum of the angular momenta of the masses, so it's
possible for the sum to come to zero.  Can anyone think of a simple
demonstration?
				      - Jim Van Zandt

hull@hao.UUCP (Howard Hull) (07/12/85)

> From: jrv@Mitre-Bedford
> 
> 
> > I've been watching the comments concerning ways to overcome the gyroscopic
> > inertia problem with the OMNIMAX cameras with growing disbelief. The 'fix'
> > seems to consist of a second counterrotating mass whose angular momentum
> > is matched by various means to that of the filmreel. It won't work, of course.
> > Adding a second rotating mass, counterrotating, at right angles, or
> > whatever will simply *ADD* to the problem by creating more angular
> > momentum. You might as well try to 'cancel' some mass by adding some
> > mass in another place; it just doesn't work that way.
> 
> Of course it works that way.  The angular momentum of a collection of
> masses is a vector sum of the angular momenta of the masses, so it's
> possible for the sum to come to zero.  Can anyone think of a simple
> demonstration?
> 				      - Jim Van Zandt
Sure.  Two skaters spin up in opposite directions, approach each other, and
then lock arms.  Presto, net zero angular momentum.  If the proposed theory
is correct, all of the atoms in both their livers will be found to be spinning
in opposite directions...
								     Howard Hull
[If yet unproven concepts are outlawed in the range of discussion...
                   ...Then only the deranged will discuss yet unproven concepts]
        {ucbvax!hplabs | allegra!nbires | harpo!seismo } !hao!hull