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August 20th 03, 06:47 AM

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If you notice, the strain is = delta L/ original L, so the strain
is dimensionless.

Yes, and no. It was length per length, not, for example, volt per volt
or
pound per pound or ...

But it's still dimensionless, a "pure number" as they call it.

So dimensionless quantities are not all the same, even though they are
all dimensionless.

In context, i would agree, but they are still just pure numbers.

Hunh?? how did you get radians = m/m?

Length of arc divided by radius in MKS units. How quickly we forget when
we get in the habit of leaving out all the units.

ok, length of angle divided by length of radius, that's right.

After multiplying Torque by Radians, you have computed the length
along the arc through which the force has acted - energy, of course.

Actually, you've done 2*pi*radius*force work. Moving one circumference
times the force.

Actually, thats 2*pi*radius*force*moment arm. Right.

...Keith

Basic algebra and cancellation of units. When have you found it
not to be appropriate?

It is not appropriate to consider Torque and Work to be the same, though
they have the same units.

Your point it well taken, but cancellation of units has always
worked for me, and everyone else i went to college and high school
with.

And I admit that a wave traveling in a transmission line is
different from an EM wave traveling through space. All i'm saying is
that the E field is defined by a voltage potential field, and the H
field by amperes, so to say that the E field has nothing to do with
voltage potential is a wrong statement in my opinion. And it's still
ohms for the impedance.

It is not appropriate to consider modulus of elasticity and pressure
to be the same, though they have the same units after simplification.

But after multiplying Torque times Radians it is necessary to simplify
to discover that Work is the result.

I conclude that simplification is sometimes necessary and appropriate
but other times it is not. I am having difficulty knowing how to know
when it is appropriate.

This brings us back to the Ohms of free space and the Ohms of a
resistor.

While I don't know whether they are the same or not (and opinion seems
divided), it is clear that arguing that they are the same because the
units (after simplification) are the same is quite falacious. On the
other hand if the units were different, it would be clear that they
are not the same.

...Keith

It's a difficult question, and i'm glad we are discussing it. All
i'm saying is, the units have to be the same, where ever you use them.

Slick

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