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Re: N2



In his 7/4/00 Phys-L post "Re: N2," Jack Uretsky writes:

"Dick Hake, when he was at Indiana, developed an N2 lab that
involved students pushing masses around and making sketches to
describe their observations and reactions. This type of activity is,
I think, much more effective in developing kinesthetic intuition than
are the "experiments" I've seen described on this thread. Perhaps Dick
can be persuaded to put his N2 lab on the net so that you can see what
I am talking about."

Of course, I agree completely with Jack. Nine Socratic Dialogue
Inducing (SDI) labs,(1,2) including three on N2, are on the web at
<http://www.physics.indiana.edu/~sdi/>.

Beyond developing "kinesthetic intuition," those who worry about the
circularity of standard introductory labs which purport to "verify" F
= ma, might consider SDI Lab #6, "Newton's Second Law Revisited."(3)
Here a force probe and sonic motion detector are used to actualize a
thought experiment suggested by Arons(4): a force scale is calibrated
in terms of the extension of a spring attached to a standard body
which undergoes various constant accelerations on a horizontal
runway. The inertial mass m of any body is then operationally
defined in terms of the ratio F/a.

Richard Hake, Emeritus Professor of Physics, Indiana University
24245 Hatteras Street, Woodland Hills, CA 91367
<rrhake@earthlink.net>
<http://www.physics.indiana.edu/~hake>


REFERENCES AND FOOTNOTES
1. (a)R.R. Hake, "Promoting student crossover to the Newtonian
world," Am J. Phys. 55, 878-884 (1987); (b) S. Tobias and R.R. Hake,
"Professors as physics students: What can they teach us?" Am. J.
Phys. 56, 786-794
(1988); (c)"Socratic Pedagogy in the Introductory Physics Lab," Phys.
Teach. 30, 546-552 (1992) and at
<http://www.physics.indiana.edu/~sdi/>.

2. J.L. Uretsky, "Using 'Dialogue Labs' in a Community-College
Physics Course," Phys. Teach. 31, 478-481 (1993).

3. R.R. Hake and R. Wakeland, "What's F? What's m? What's a?: A
Non-Circular SDI-TST-Lab Treatment of Newton's Second Law," in
"Conference on the Introductory Physics Course," Jack Wilson, ed.
(Wiley, 1997), p. 277-283.

4. A. B. Arons, "A Guide To Introductory Physics Teaching" (Wiley,
1990), p. 52-55; reprinted with minor updates in "Teaching
Introductory Physics" (Wiley, 1997) [also contains Homework and Test
Questions for
Introductory Physics Teaching (Wiley, 1994) along with a new
monograph "Introduction to Classical Conservation Laws"].