Re: What Flows?

[palmer@sfu.ca (Leigh Palmer)]

> But, Leigh, physical quantities are not merely magnitudes.  They have
> dimension.  Isn't this what distinguishes one physical quantity from
> another as in velocity as compared to acceleration?

The magnitude of a torque is a physical quantity, just as speed is.

> I'm not talking about "other" combinations or operations which we do not
> normally do, but does not the same thing apply?  Different operations
> result in different combinations of dimensions?

Do you "normally" use complex numbers? You are certainly adding
together quantities which differ in much the same way as scalars
and vectors do. Is reactance not measured in the same units as
resistance? Does impedance have a physical meaning?

> > The bottom line is this: energy and torque have the same
> > dimensions. They can be given the same units, too, but
> > there is probably a lot to be said for distinguishing
> > them by using cosmetically different units.
>
> So you're telling me that you can refer to the physical quantity, 5 Joules,
> and this could be either a torque or an energy?  What happened to all the
> precision in language?

"5 joules" is not a physical quantity. Work is a physical quantity,
torque is a physical quantity, and energy is a physical quantity.
Perhaps I'm being abrupt, but I really don't think I have
understood the question you are asking. As a result I'm reduced to
simple reiteration, though of course I don't believe strongly in
Lewis Carroll's "What I tell you three times is true".

Leigh