VtSkier wrote:


Having read the wiki, I don't see much difference
in what I've been saying.

Here are the differences:

You are confusing two distinct concepts, torque and work. They are
different but related ideas. They are *not* the same.

You are saying that torque is not a vector. It is.

You are saying that there must be motion to have torque. Not true. See
below.


In all of the wiki, I can find no instance where
if there is no motion there is torque.


Look again. Here's the definition of torque:

Mathematically, the torque on a particle (which has the
position r in some reference frame) can be defined as
the cross product:

Tau = r X F

where

r is the particle's position vector
F is the force acting on the particle,

So, to have torque, all you need is a force. There does not have to be
motion. It's the cross product of two vectors, so it is by definition a
vector.


Stated the other way, if there is no motion, there
is no torque.

No.

Think of it this way: I'm testing a binding. I place a boot in the
binding and apply a torque of, say, 50 Newton Meters. The binding
doesn't release. I've just described a situation where there is torque
but no motion. Do you say there is no torque here? If so, how does one
ever test a binding?

torque is work in a rotational or angular mode.

Torque produces work when there is motion, according to W = T dot theta
(where theta is the angle the torque moves through and dot is the vector
dot product). The relationship between torque and work is very simple,
but the two are different concepts.

Similarly, force produces work when there is motion, according to W = F
dot d (where d is the distance the force acts through and again dot is
the vector dot product). Here force and work are related in a very
simple manner, but that doesn't mean that force *is* work. They are
different but related concepts.

In particular, force can exist without motion. When that happens, there
is no work. Likewise torque can exist without motion. Again there is
no work if there is no motion.


//Walt