MadSci Network: Physics |
Hi Vince,
thanks for your mail. I found quite a good resource on the web, I will
quote from there:
"To understand the concept of work, it is
necessary to
develop some intuition about it. To this end, a force F acting on a
particle
and displacing it through a small distance dr as shown in the figure may be
considered. The work done by the force must
somehow be related to the "effort put in" by the agency that is responsible
for the application of the force. This effort must be
related to the magnitude of the applied force, i.e., if the applied force
is larger, the work done must be larger (for a given dr).
Similarly, the "effort" must be proportional to the distance moved, i.e.,
the work done by the given force F will be larger if it
moves through a larger distance. In other words, the magnitude of "work
done" should increase with the magnitude of the force
and the displacement produced by that force. It seems reasonable to define
the infinitesimal work done by a force F moving a
body through an infinitesimal distance dr to be dU=F * dr."
In the remarks you find, I think, an answer to your question that Watt "did
not know" what he was measuring:" 1.It must be emphasized that the work
done is a scalar quantity that was defined. In other words, it contains no
new information other than the force and the displacement. The only
difference is that the information is contained in adifferent, and
sometimes very useful, form. "
So, Watt maybe did not have the formal concept of "Work", but it
nevertheless was work what he was measuring.
Have a look at the webpage http://www.engin.brown.edu/courses/en4/notes/workenergy/workenergy.html
, it is really worth it!.
Bye,
Andreas
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