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From: throopw@rtp47.UUCP (Wayne Throop)
Newsgroups: net.physics
Subject: Re: Question... [On tilt-meters in off-road vehicles]
Message-ID: <177@rtp47.UUCP>
Date: Sat, 7-Sep-85 17:04:39 EDT
Article-I.D.: rtp47.177
Posted: Sat Sep  7 17:04:39 1985
Date-Received: Mon, 9-Sep-85 04:39:12 EDT
References: <29@decwrl.UUCP> <10041@ucbvax.ARPA> <291@ecsvax.UUCP> <271@aoa.UUCP> <163@rtp47.UUCP> <282@aoa.UUCP>
Organization: Data General, RTP, NC
Lines: 49

Well, I'm still looking for enlightenment with regard to
momentum-nature (:-).  The story so far:

> > > [Original posting asserting there is a non-symmetric effect in a
> > > spinning wheel when turned left vs. when turned right, and
> > > instructions to meditate on the picture of a precessing top in
> > > Halliday & Resnick to be enlightened as to the nature of this
> > > non-symmetric effect.]

> > OK.  I went and looked at my Haliday&Resnick picture of a top
> > precessing.  I'm still not enlightened.  In what way will this effect
> > cause a car to be more stable turning left than right?

> I'm far to fogyheaded to remember which way the precession and force go,
> but you can check it out bysitting on a bar stool (the rotating kind),
> holding a bicycle wheel, spinning it up, then rotating the wheel on its
> axis.

OK.  I went and got a barstool and a spinning bicycle tire.  (Don't you
just love obeying strange directions gotten from a computer?) I'm still
not enlightened.  The effects I could discover are completely symmetric
with respect to left and right.  Unless somebody comes up with a *much*
more convincing koan (:-), I'm still assuming that there is *no such
(asymmetric) effect*.

--
Truth in advertising leads me to comment that I didn't get a barstool
and a tire, but I *did* get a gyroscope and a rig to put it in, and
observed the effects.  These are the same effects mentioned in Halliday
& Resnick, and are, as mentioned above, completely symmetric with
respect to left and right.  In case it is interesting, in both
directions of turn there was *more* tipping force due to gyroscopic
effects.

In particular, the spinning tire has a momentum vector pointing left.  A
left turn introduces a vector pointing up.  The gyroscopic effects
create a vector pointing forward.  In a right turn, the introduced
vector points down, and the gyroscopic vector points back.  All neatly
symmetric.  Carrying it further to the precessional rotations results in
the same symmetry (since any precessional rotations reverse direction
with a reverse in turn direction).  Is there some non-symmetric effect
I'm missing?  I can comment from my experiments that if the effect
exists, it is *very* small compared with the gyroscopic effects I
observed.

(And all you net.zen.buddists out there don't need to beat me over the
 head with a stick and shout "MU", either!  :-)
-- 
Wayne Throop at Data General, RTP, NC
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