On Sat, 25 Oct 2003, Laurel Amberdine wrote:

On Fri, 24 Oct 2003 21:38:11 -0500, David Moran wrote:
Hi,

I am a physics student with a physical disability that limits my motor
skills. I am wondering if there are any alternatives to the right hand rule.
I understand the the principle, but my motor skills make it difficult to
carry out. Any help would be appreciated..

You might try Timo's attempt to help me with the right hand rule a few
days ago in the thread titled " Vectors". There are a lot of comments
on the same topic in that thread.

Which was simply:

just with your right hand in an open relaxed state, find the direction of
a vector cross-product by:

thumb x fingers = out from palm.

All of the various right-hand rules relate to that order of three
driections: thumb, fingers, palm. If your motor skills are such that you
can't easily move your hand into a suitable position, next easiest might
just be to memorise the simple combinations for diagrams on a sheet of
paper:

right x up = towards you
left x up = away

and any other combination of vectors in the same plane as the paper, just
rotate this

Then:

right x away = up
left x away = down

etc

If you can rotate the directions around mentally, it's much easier, you
don't need to move your right hand at all; just remember the magic order:

thumb x fingers = palm.

This, by the way, is why the usual xyz Cartesian coordinate system is
called right-handed, x, y, z are in the thumb, finger, palm directions.

(I see that most 6-sided dice are right-handed, but I see occasional
left-handed dice. Is there an official standard, and how does it describe
the handedness of dice? Is this just a modern thing - ie were ancient
dice "ambidextrous"?)

--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html