Robert Bossy wrote: > In my mind, the second mistake was the confusion between weight and mass.
I see. If so, then that sounds like another terminology gotcha. The distinction between weight and mass is all but irrelevant for everyday activities, since the acceleration due to gravity is so nearly constant for all circumstances under which non-physicists operate in everyday life. Not only in everyday life does the terminal speed of a falling object depend on its mass (m) -- among other things -- but that is also equivalent to that speed depending on its weight (m g_0). Physicists even talk about a "standard gravity" or "acceleration due to gravity" being an accepted constant (g_0 = 9.806 65 m/s^2), and most SI guidelines, including NIST's, fully acknowledge the effective equivalence for everyday usage and make no requirement of using the "proper" units for mass (kg) vs. weight (N) for, say, buying things at the store, even though it's technically wrong (where "weight" is given in kilograms even though that's not a unit of weight, but rather of mass). To put it another way, there are far better ways to teach physics than this, because these misunderstanding are not wrong in any meaningfully useful way. -- Erik Max Francis && [EMAIL PROTECTED] && http://www.alcyone.com/max/ San Jose, CA, USA && 37 18 N 121 57 W && AIM, Y!M erikmaxfrancis It isn't important to come out on top, what matters is to be the one who comes out alive. -- Bertolt Brecht, 1898-1956 -- http://mail.python.org/mailman/listinfo/python-list
