High School SMILE Meeting
02 May 2006
NOTES OF OUR FINAL SMILE MEETING -- EVER !!
Porter Johnson (IIT
physics)
Future Plans
Porter discussed plans for more complete development of the
SMILE and
SMART websites over
the summer. The database of academic year mathematics and physics
lessons is located at AcademicYearbyCategory
It has been arranged by category as follows:
According to plans, math and physics lessons for the 2005-2006 Academic Year will be added to this database during Summer 2006. In addition, the lessons will be further divided into subcategories and rearranged, as appropriate. In addition the recent academic year lessons in high school biology and chemistry will be organized on the SMART website. This database will be maintained for the foreseeable future.
The SMILE website will be officially finalized and organized to include such items as The History of The SMILE Program 1986 - 2006, descriptions by staff members and participants of the impact of the SMILE Program on their professional lives, etc. Anybody who wishes to provide a written account of their personal experience in the program should send it in electronic form to me. [Porter.Johnson@iit.edu or johnsonpo@iit.edu].
Brenda
Daniel (Fuller Elementary
School)
Time for Kids ®
Brenda distributed copies of the version of Time Magazine
for
children -- provided gratis -- to her 4th grade class. The children
enjoy
reading this magazine [http://www.timeforkids.com],
which has dealt with scientific topics such Pluto and planet X,
the effects of
smoking on health, and ecological systems. The
magazines also strengthen the skills needed for taking the ISAT
tests.
Teachers were supplied with teachers’
guides, sample projects, and the like with each issue of the magazine.
Worth knowing! Thanks, Brenda.
Nneka Anigbogu (Jones College Prep,
math)
Math Ideas for Non-College
Prep Students
Nneka showed us a way to teach
exponential decay using M&Ms® or Skittles®!
We divided
into three groups, each with a small bag of M&M’s and a
medium sized plastic cup. We counted the number of candies
in our bag and put them into the cup (53-55 were the numbers
to start). Then we shook the cup and tossed the M&Ms
out (like dice) and counted the M&M’s with the M
showing
(heads up). The candy pieces that landed with the M up were
put back into the cup,
which was shaken and tossed once more. Again, about half of them
remained. We continued the process.
Here are the data recorded in tabular form for the groups:
M&M's Toss | |||
Trial Number | Group #1 | Group #2 | Group #3 |
1 | 53 | 55 | 54 |
2 | 29 | 25 | 21 |
3 | 14 | 08 | 16 |
4 | 05 | 08 | 07 |
5 | 00 | 04 | 02 |
6 | - | 02 | 01 |
7 | - | 01 | 00 |
8 | - | 00 | - |
She drew a graph of the number of M&M’s remaining versus the number of tosses, obtaining a profile that looked roughly exponential. She estimated the parameter r by using the formula Y2 = Y1 (1 - r), or
We obtained r = 0.45, 0.55, and 0.57 for the three cases -- the extrapolated numbers using these values of r being fairly close to the actual results.
For more candy games see the M&M's website: http://us.mms.com/us/fungames/games/. A good Phenomenological lesson -- edible too! Thanks, Nneka.
Walter Kondratko (Fenger HS,
chemistry)
Stuff From Class
Walter
showed us a crystal that was grown in his class; the kit can be
ordered on the
website http://scientificsonline.com/product.asp?pn=3081666&cmss=grow+crystal.
Walter then showed us a Crookes tube http://en.wikipedia.org/wiki/Crookes_tube.
A current was passed through the tube, using a high voltage
source (5000 Volts --
without the ballast circuit usually found in house fluorescent lights).
A fluorescent
coated strip mounted vertically within the tube allowed us to see
the path of a beam of electrons through the tube. Walter
showed that the beam could be deflected up or down with a horseshoe
magnet.
Then he showed
us a ball and stick model of an amino acid to illustrate
chirality/enantiaomers [http://www.brynmawr.edu/Acads/Chem/mnerzsto/PolarimetryExercise.htm],
and showed that they were mirror image
isomers, which are not geometrically identical. These amino acids
produce
optical rotation. The plane of
polarization of light rotates in different directions for dextrorotary
(right-rotating) and levorotary (left-rotating) compounds..
For
details see Stereochemistry Tutorial: http://facultystaff.vwc.edu/~jeaster/courseinfo/Tutorials/stereochemistryl.html.
Beautiful
phenomena -- quite illuminating! Thanks Walter.
Bill Blunk (Joliet Central HS,
retired)
Giveaways
Bill
gave us 3 slides of pictures in an article about the release of a
captured grizzly bear by the Montana Division of Natural Resources
in
1987. The culvert trap was not properly secured to the bed of the
pickup
truck. When the grizzly turned and tried to attack a ranger atop
the
culvert track, the driver gunned the engine and drove the truck out
from under
the trap and ranger. Lack of knowledge of Newton's First Law resulted
in an injured driver, and the bear was subsequently killed.
Physics rules! Thanks, Bill.
Arlyn VanEk (Illiana Christian HS,
physics)
Impedance Matching
Arlyn held one end of a piece of rope, and a volunteer held the
other
end. Arlyn then shook his end of the rope up and down,
while the volunteer held
the other end fixed. By adjusting the tension in
the rope, Arlyn was able to set up a standing wave with two
nodes.
He reduced the tension, and was able to get standing waves with one
internal
node, and with no internal nodes at all. By moving his end in a
circular
path, Arlyn was able to set up a spiral standing wave. He then
tied an equal length
of lighter rope to the heavier one, and the
process was repeated. Arlyn was unable to produce any
standing
waves in this case. With the double rope held fixed under
tension, Arlyn
plucked his end, and the resulting pulse traveled toward the other end.
But when
the pulse got to
the point where the two ropes were connected, it was partially
reflected and partially
transmitted. How
come? Arlyn said that there was a mismatch in the (mechanical)
impedance at the junction.
The mechanical impedance of a vibrating system is defined in analogy to the electrical impedance of an electric circuit [for details see T.D. Rossing and N.H. Fletcher, Principles of Vibration and Sound -- Springer Verlag 1994, ISBN 0-387-94336-6], as illustrated in the table below: [Note: i = Ö(-1) and j = -i.]
IMPEDANCE |
||
Item | Electrical | Mechanical |
Driving Term | Voltage: V0 e-iwt | Force: F0 e-iwt |
Response | Current: I0 e-iwt | Velocity: v0 e-iwt |
Impedance | Z(w) = V0 / I0 | Z(w)= F0 / v0 |
Dynamics | L I ' + RI + Q/C = V | mv' + Rv + kx = F |
Form | Z = R + j (wL -1/(wC)) | Z0 = R + j (wm - k/w) |
In both cases, the relevant impedance must match for smooth transfer of energy from one system to another.
Let us consider the (small) transverse displacement of an ideal flexible string of length L that is held fixed at x = 0 and terminated at x = L. Using the formula y(x,t) = A sin kx e-iwt, the corresponding transverse velocity is v(x,t) = -i wA sin kx e-iwt. The transverse force exerted by the string at x = L is equal to T (¶ y/¶ x) evaluated at x = L, which equals kT cos kL e-iwt. The mechanical impedance is the ratio of the transverse force to the velocity x = L. We obtain:
If you taper a rope gently (like a whip) you can transfer the wave all
the way down to
the tip of the whip. Arlyn used a real bull whip to show this,
and it
made a loud crack -- a sonic boom. For additional details see The
Shape of a
Cracking Whip: http://www.npr.org/programs/wesat/features/2002/june/whip/index.html.
The whip is an impedance transformer. A megaphone is another
example of an
impedance transformer, where the megaphone makes a gradual
change for the air within the cone, from warm near the mouth
to cooler air near the end of the megaphone.
Cracking phenomenological physics, Arlyn. Thanks.
Erik Jurgens (Joliet West HS,
physics)
Going From a Circuit Schematic to the Breadboard
Erik made “components of
circuits” molded out of toilet paper rolls and boxes (to
show resistors, voltage sources, etc. with colorful yarn at either
end to represent wires. With magnets attached to the yarn
and the components, circuits could be illustrated on
the
blackboard. The students could then visualize the circuit before
setting it up
in the laboratory. An example of "roll playing"!
Very interesting and useful! Thanks, Erik.
Marva
Anyanwu (Wendell Green
Elementary
School)
Earthquakes, and Other Things
Marva
asked how many earthquakes occur in a day worldwide? It
turns out that one occurs every 10 seconds (about 3
million per year
that
register significantly on the Richter Scale; see http://neic.usgs.gov/neis/eqlists/eqstats.html).
Marva also brought in an article about the proposed
10th planet [http://www.gps.caltech.edu/~mbrown/planetlila/].
She discussed whether Pluto should be considered as a planet,
and
whether the number of planets should be 8, 9, or 10. Marva
also passed out a table listing the densities of planets in the solar
system: http://www.enchantedlearning.com/subjects/astronomy/planets/
Fascinating, Marva! Thanks.
Bill Colson (Morgan Park HS,
math)
Interesting Websites
Bill learned about the following interesting websites from Make
Magazine, Vol 05 http://www.makezine.com/:
Thanks, Bill!
Porter Johnson (IIT
physics)
Shroud of Turin Project
Porter learned about a Shroud of Turin Project website
from
Steve Feld, Editor of ThinkQuest NYC Newsletter: http://shroud2000.com/LatestNews.htm.
The site is featured on the Landmarks for Schools homepage
http://landmark-project.com/index.php. The website describes
scientific investigations on the authenticity of The Shroud of
Turin.
It gives a link to various English and Greek Language versions
of a Biblical
eye-witness
account in the Gospel of John, Chapter 20, verse 7, in which
the shroud
of Jesus is specifically mentioned [Online Parallel Bible:
http://bible.cc/john/20-7.htm].
Finally, it provides information to
suggest that Leonardo DaVinci may actually have created the
shroud,
discussing his motivations as well as his capabilities. A
re-creation of a Shroud Image has recently been done by
Stephen Beckman,
using a camera obscura -- along with other materials and
technology available in Leonardo's era. This Shroud of Turin
website is
http://shroud2000.com/LatestNews.htm.
The website merely presents the information, allowing visitors to the
website to
express their own opinions on this subject. The results of an
online poll
are presented. The project provides an excellent example of
Scientific
Inquiry! Thanks.
The following people were unable to do their presentations because we ran out of time. If a written version is available, we will post it. Please send it electronically to Porter Johnson at this email address: Porter.Johnson@iit.edu.
Notes prepared by Ben Stark and Porter Johnson.