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Re: Good labs for circular motion/centripetal acceleration



In an AP Physics post of 2 Nov 2004 21:42:53 GMT, Kerrie McKinstry, a
teacher at Swampscott High School in Massachusetts, wrote:

"I am looking for some challenging but interesting labs involving circular
motion and centripetal acceleration."

As an alumnus of Swampscott High School (class of 1945), I should
like to suggest Socratic Dialogue Inducing (SDI) Lab #3 "Circular
Motion and Frictional Forces."

The SDI Lab #3 manual may be freely downloaded as a 278kB pdf
<http://www.physics.indiana.edu/~sdi>.

An SDI Lab #3 Teacher's Guide is available as a 764 kB pdf at
<http://galileo.harvard.edu/> / "Socratic Dialogue Inducing Labs"
/"Resources for SDI" (under "What are the requirements" / "Teacher's
Guides", where "/" means "click on." The Galileo site is being
revamped, so if you have trouble accessing this please let me know.

Among the uniform circular motion topics of SDI Lab #3 are:

I. Vectors F, v, a, and Angular Velocity For Various Bodies In
Uniform Circular Motion:

A. Bucket of Water (See Hake 1992 - "Water Bucket Swing" - Why
doesn't the water fall out of the bucket when swung over the head in
a vertical circle?)

B. The Moon (Why doesn't the Moon fall down to Earth?)

C. Conical Pendulum


II. FRICTIONAL FORCES IN CIRCULAR MOTION
A. Frictional Force on a Cube Rotating on a Turntable

B. Critical Value of Angular Velocity for Fly-off From the Table

C. Variables Affecting the Above

D. Limiting Conditions

E. Super Splash Spinner - A Thought Experiment: "At the 'National
Physics-Fun Amusement Park' you and the rest of the class pile on the
'Super Splash Spinner,' a giant motorized version of the turntable
used in this lab. The spinner's angular velocity omega is very
gradually and uniformly increased from zero. One by one your
classmates fly off the spinner and splash into the surrounding pool.
(Would it be wise to wave goodbye to them?) As omega increases you
consider the Newtonian physics of the critical value omega(c) for
your fly-off from the spinner. The coefficient of static friction
between you and the spinner is mu(s). Your mass is m. Ignore air
friction.

F. Experimental Measurement of the Coefficient of Static Friction and
the Critical Angular Velocity for Fly-off From the Table


III. ROTATING REFERENCE FRAMES
A. Playing Catch on a Merry-Go-Round [adapted from Evans (1982)].

B. Cyclone and Bathtub Vortices [See Hake (1994).] A plastic-pail
bathtub is placed on a giant merry-go-round with an angular velocity
omega about 10^4 greater than that of the Earth. Merry-go-round
rotations simulating northern and southern hemispheres then result in
water vortices around the drain that are, respectively, consistently
counterclockwise and clockwise.

C. Connection Between "A and "B"

Socratic Dialogue Inducing (SDI) Labs have been discussed in e.g.,
Hake (1992, 2002a). They were written primarily for undergraduates,
but have been used successfully in some high schools [see e.g.,
Butterworth (2002)] and even in middle schools [Priestly (2002)].

They can be changed to suit local conditions by copying sections of
the pdf; pasting them into a word processing document; and then
editing - but please don't propagate your version beyond your own
school.

Unfortunately, the Socratic Method has been grossly misunderstood by
some [e.g., Morse (1994), Redish (2003)] as equivalent to the
PLATONIC method described in Plato's Meno. For the real Socratic
Method see Hake (2002b,c,d).

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


REFERENCES
Butterworth, S. 2002. "Re: Socratic Method," Physhare post of 15 Nov
2002 18:32:46 +0200; online at
<http://lists.psu.edu/cgi-bin/wa?A2=ind0211&L=physhare&P=R5911&I=-3&X=15F48B27A38D72E1C1&Y=rrhake%40earthlink%2Enet>.
The encyclopedic URL indicates that Physhare archives are open only
to non-subscribers. However, it takes only a few minutes to subscribe
by following the simple directions at
<http://lists.psu.edu/archives/physhare.html>/ "Join or leave the
list (or change settings)" where "/" means "click on." If you're
busy, then subscribe using the "NOMAIL" option under "Miscellaneous."
Then, as a subscriber, you may access the archives and/or post
messages at any time, while receiving NO MAIL from the list!

Evans, L. 1982. "The Coriolis Effect and other Spin-Off
Demonstrations," Phys. Teach. 20: 102.

Hake, R.R. 1992. "Socratic pedagogy in the introductory physics lab,"
Phys. Teach. 30: 546-552; updated version (4/27/98) online as ref. 23
at <http://www.physics.indiana.edu/~hake>.

Hake, R.R. 1994. "More on Coriolis myths and draining bathtubs," Am.
J. Phys. 62(12): 1063.

Hake. R.R. 2002a. "Socratic Dialogue Inducing Laboratory Workshop,"
"Proceedings of the UNESCO-ASPEN Workshop on Active Learning in
Physics," Univ. of Peradeniya, Sri Lanka, 2-4 Dec. 2002; also online
as ref. 28 at <http://www.physics.indiana.edu/~hake/>. [ASPEN = ASian
Physics Education Network
<http://www.swin.edu.au/physics/aspen/welcome.htm>.]

Hake, R.R. 2002b. "Re: Socratic Method,"
Phys-L/PhysLrnR/Physhare/AP-Physics post of 14 Nov 2002
14:32:54-0800; online at
<http://lists.nau.edu/cgi-bin/wa?A2=ind0211&L=phys-l&P=R9157>.

Hake, R.R. 2002c. "Re: Socratic Method,"
Phys-L/PhysLrnR/Physhare/AP-Physics post of 13 Dec 2002
13:33:26-0800; online at
<http://lists.nau.edu/cgi-bin/wa?A2=ind0212&L=phys-l&P=R15999>.

Hake, R.R. 2002d. "Re: Socratic Method,"
Phys-L/PhysLrnR/Physhare/AP-Physics post of 18 Dec 2002
17:48:07-0800; online at
<http://lists.nau.edu/cgi-bin/wa?A2=ind0212&L=phys-l&P=R19258>.

Morse, R.A. 1994. "The Classic Method of Mrs. Socrates," Phys. Teach.
32: 276-277.

Priestley, H. 2002. "Re: Socratic Method," PhysLrnR post of 16 Nov
2002 16:28:54-0500; online at
<http://listserv.boisestate.edu/cgi-bin/wa?A2=ind0211&L=physlrnr&P=R6118&I=-3&X=638E0D1402421CA568&Y=rrhake@earthlink.net>.
The encyclopedic URL indicates that PhysLrnR archives open only to
non-subscribers. However, it takes only a few minutes to subscribe by
following the simple directions at
<http://listserv.boisestate.edu/archives/physlrnr.html>/ "Join or
leave the list (or change settings)" where "/" means "click on." If
you're busy, then subscribe using the "NOMAIL" option under
"Miscellaneous." Then, as a subscriber, you may access the archives
and/or post messages at any time, while receiving NO MAIL from the
list!

Redish, E.F. 2003 "Teaching Physics With the Physics Suite" (TPWPS),
John Wiley, footnote 5 page 146. TPWPS is online at
<http://www.physics.umd.edu/perg/>, scroll to the bottom of the page.