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Re: Inertia



In an 11/28/97 Phys-L posting of the above title Patrick Whippey writes:

=93Arnold Aron's book =91A Guide to Introductory Physics Teaching=92 Wile=
y,
1990 has a very careful discussion of this issue...(the meaning of F and
m in Newton=92s Second Law)... He has written another book very recently,
and that too will probably have wise words.=94

In the last sentence, Patrick is evidently referring to =93Teaching
Introductory Physics=94 (Wiley, 1997). That book contains minor updates
of two earlier books "A Guide to Introductory Physics Teaching" and
=93Homework and Test Questions for Introductory Physics Teaching=94 (Wile=
y,
1994), plus a new monograph =93Introduction to Classical Conservation
Laws.=94 =93Teaching Introductory Physics=94 has been reviewed by Redish =
(1).

In =93A Guide to Introductory Physics Teaching,=94 Arons suggests that
introductory-course students might be lead to a satisfactory
understanding of F and m in Newton=92s Second Law F =3D ma, by considerin=
g a
=93Newtonian sequence=94 thought experiment in which 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. That experiment has been actualized as a
student Socratic Dialogue Inducing (SDI)laboratory (2,3) using a force
probe, sonic motion detector, computer tools, and software developed at
Tufts University and utilized in =93Tools for Scientific Thinking.=94 (4)=
=20

Richard Hake, Emeritus Professor of Physics, Indiana University
24245 Hatteras Street, Woodland Hills, CA 91367


REFERENCES
1. E.F. Redish, book review, Phys. Today 50(7), 61 (1997).

2. R.R. Hake and R. Wakeland, SDI Lab # 6, =93Newton=92s Second Law
Revisited,=94 available at <http://carini.physics.indiana.edu/SDI/>.

3. R.R. Hake and R. Wakeland, =93What=92s F? What=92s m? What=92s a?: A
Non-Circular SDI-TST-Lab Treatment of Newton=92s Second Law,=94 in
=93Conference on the Introductory Physics Course,=94 Jack Wilson, ed.
(Wiley, 1997), p. 277.

4. R.K. Thornton and D.R. Sokoloff, =93Learning motion concepts using
real-time microcomputer-based laboratory tools,=94 Am. J. Phys. 58, 858
(1990).