Re: [Phys-l] "Flow" again (or still if you prefer)

["Robert Cohen" <Robert.Cohen@po-box.esu.edu>]

At 09:08 PM 5/18/2006, Jim Green wrote:
<snip>
> Which of you would prefer to think of the process as follows:
>
> The Earth does work on the weights as they fall.
> The weights do work on the strings.
> The strings do work on the paddle wheel.
> The paddle wheel does work on the water molecules.
> The average KE of the water molecules increases.
> The temperature of the water increases.
>
> Nothing "flows" -- ie energy is not reified in the mind.  
> Work is done

In general, I admit that I like thinking in terms of "work-energy"
rather than "cons. of energy" (sort of like I prefer to think of forces
"causing" accelerations or work "causing" changes in kinetic energy).
However, I can't really answer whether I "prefer" it until you explain
who the audience is (e.g., I don't like telling students that forces
"cause" accelerations).

> If you would not prefer the preceeding, would you sympathize 
> with this explanation?

One problem I have is that it is sometimes a long-winded way of talking
about things.  The wording also seems to imply that the earth is the
only thing doing work on the weights, the weights are speeding up and/or
there is a significant time-delay between each step, as though it takes
time before each "object" has enough "something" to "do work" on the
next object (or that "information" about the work flows from one object
to the next).  I don't really mind the description you provide because I
know what you "mean."

> Some other set of feelings?

When talking to other people I tend to just say "the energy associated
with the earth/weight system decreased and the energy associated with
the water temperature increased."

Hope I've addressed your questions adequately with my opinions and
wonder where you are going with this (and hope it is someplace other
than where we've gone in the past).

____________________________________________________
Robert Cohen, Chair, Department of Physics
East Stroudsburg University; E. Stroudsburg, PA 18301
570-422-3428; www.esu.edu/~bbq