I think we need to recognize the difference between a definition and a
theoretical/empirical relationship*. If we define the average v to be the
ratio x/t, that does not mean that the average v increases if x increases
or that x somehow causes v. Similarly, if we define the resistance R to
be the ratio V/I, that doesn't mean that R is constant or that V somehow
causes R or that R is inversely proportional to I.
Yes, students get the two confused (i.e., definitions and
theoretical/empirical relationships). It is easy to confuse equations
like v = v_0 + a*t and v = dx/dt. Perhaps we need to use a different
symbol (e.g., three parallel lines) when using definitions?
*I suppose I'm implying my opinion means something. I shouldn't. :)
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| Robert Cohen Department of Physics |
| East Stroudsburg University |
| bbq@esu.edu East Stroudsburg, PA 18301 |
| http://www.esu.edu/~bbq/ (570) 422-3428 |
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