Re: Torque, moment, and couple

[Leigh Palmer <palmer@SFU.CA>]

Bob writes:

> I once submitted an article to AJP detailing a unified treatment of ang mom
> which explicitly carries two appropriate subscripts.  The article was
> rejected as adding unneeded complications.

It seems to me that angular momentum of a particle only makes sense
when velocities are reckoned with respect to the frame in which the
reference point for the angular momentum is stationary. How would
one use the quantity r x (m * v) in any frame other then the one in
which v = dp/dt?

One more thing should be mentioned regarding the physical nature of
torque. Torque is not, strictly speaking, a vector quantity. Vector
quantities are associated with an intrinsic direction. No one has to
explain which direction is meant when specifying a force or velocity,
both of which are vector quantities. Torque, like angular momentum
and magnetic field, is axial, but not directional. In Gibbsian terms
it is a "pseudovector". It would be called a "bivector" in Clifford
algebraic terms.

Leigh