From: "JACK L. URETSKY (C)1998; HEP DIVISION, ARGONNE NATIONAL LAB ARGONNE, IL 60439" <JLU@HEP.ANL.GOV>
Date: Mon, 23 Aug 1999 23:35:48 -0500
This experiment, as I have seen it, involves a sliding mass on an
inclined air track. The mass is released from rest and slides a fixed and
measured distance through a velocity measuring device. The distance from
the point of release to the velocity measuring device is varied so that one
measures the variation of distance traveled vs velocity. The instructions
state the expected functional relationship between the two quanitities, so
the student is invited to measure the (constant) value of the acceleration and
, with some trig, the value of g. Truly, a mind-numbing exercise.
I suggest the following variation on this experiment. If the acceleration
were a power, say a, of the time of travel, then the distance traveled would
vary as a power 1 + 1/(a+1) of the final velocity of the mass. Now for those
who would yell YOU'RE WRONG! to those who would propose that a is different
from zero, I invite you to determine limits on a from a real experiment. I
suggest, therefore, that instead of using this experiment to determine the
constant g, the experiment be used to determine acceptable ranges of a. I
think that I can guarantee that a=0 is not an assured outcome.
P.S. I once tried, in a lab, to duplicate the Galileo inclined plane
experiments. All the inclined planes I could find were badly warped, and the
results varied widely from the expected. It is my private opinion that Galileo
"cooked" his results - go for it, inquisition! Well, Newton was caught cooking
too, therby demonstrating the power of abstraction from uncertain experimental
results.
Regards,
Jack
"These several facts prove nothing, for one cannot deduce a principle from so
few examples, but they do at least indicate that the ability to learn to spell
correctly is a gift; that it is born in a person, and that it is a sign of
intellectual inferiority. By parity of reasoning, its absence is a sign of
great mental power."
Mark Twain, "Extract from Eve's Diary'.