|MadSci Network: Physics|
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!.
Try the links in the MadSci Library for more information on Physics.