ISPP REMINDER
January 2007
HAPPY NEW YEAR ! !
OUR NEXT MEETING. . .
the Annual Tri Physics Meeting: ISPP, Physics West and Physics Northwest
. . . is at Elmhurst College
Wednesday
January 17
NOTE TIME -------- 5:30 - 9:00 p.m.
5:30 for Pizza before the regular meeting at 6:30. A map and directions are enclosed.
THE FREE GIVEAWAY . . .
. . . is always a neat thing at Elmhurst, thanks to the ingenuity of Earl Swallow our host there! Can you guess what it will be?
FUTURE MEETINGS. . .
January 17 (Wednesday) Elmhurst College - Earl Swallow
February 13 (Tuesday) Northeastern Illinois University - Paul Dolan/Joe Hermanek
Mar 7 (Wednesday) Chicago State University - Mel Sabella/Sam Bowen
Apr 3 (Tuesday) Lake Forest College - Mike Kash/Bailey Donnally
May 7 (Monday) Northwestern University - Art Schmidt
June 5 or 12 (tentative) Columbia College or Museum of Science and Industry
THE 33rd CHICAGO REGIONAL BRIDGE BUILDING CONTESTS...
...will be held on... February 15, 2007 Thursday at IIT.
ALL information is available at http://www.iit.edu/~hsbridge, including where, how, when to get your bridge kits.
Contact Phyllis or Cathy at (312) 567-3025, IIT, to buy kits. At the Web site you will find the Rules and all other details.
NOW is the time to get your students involved. Ask any colleagues you may meet at ISPP, Physics Northwest, Physics West meetings, and they will be happy to tell you about its value to motivate student interest, and to help you get started!
Prof. John Kallend at IIT is the contest coordinator. Contact him at kallend@iit.edu if you have questions.
Don't miss the fun! It gets better every year!
OTHER MEETINGS . . .
CSAAPT Saturday April 14, Niles West HS, hosted by Martha Lietz and Rich DeCoster
ISAAPT Fri – Sat. March 30-31, Western Illinois University, The host is Brian Davies
AT OUR LAST MEETING.
. . .
Gerry Leitz (DePaul) welcomed us to DePaul and introduced John Milton (DePaul) to start the meeting with a phenomenon. John showed us an apparatus called a Galli Cat invented by Ron Galli that he bought from Educational Innovations ($90) The apparatus models the motion of a cat which when dropped from a few feet up will generally land on its feet. John showed us a video by the Professor Galli in which he explains how the cat moves to right itself while conserving angular momentum. John demonstrated the apparatus by holding it inverted (legs up) about a half meter above the lecture table and dropping it. After several tries the device twisted in flight and landed upright. John found several sites on the web that addressed the problem. He gave out a sheet listing all the links. He pulled up one of the sites http://www.uncyclopedia.org/wiki/Murphy's_law_application_for_antigravitatory_cats that showed us an animation of a continuously spinning cat and a “Flash Animation” site http://www.upscale.utoronto.ca/PVB/Harrison/Flash/ that described a slightly different series of steps that a cat could do to right itself. Gerry recalled how Mary Boaz who taught at DePaul many years ago would demonstrate, by swinging her arms to turn herself on a rotating chair, that while angular momentum is conserved angular position is not.
Roy Coleman (Morgan Park High School - retired) showed us an article in the IIT Biological Chemical and Physical Sciences did recently on Roy that showed a picture of his original bridge. Secondly, he held up AAPT 75th Anniversary booklet containing 75 interviews of top scientist, among those interviewed is our own Tung Jeong (Lake Forest College)
Gerry asked for new teachers in the audience. We had quite a few at this meeting: Johnathan Charnes (Moses Vines High School), George Austin (Francis Parker School), Joe Kozminski (Lewis University), Russ Jensen (St. Patrick High School), Roy McClain (Grayslake Central High School), and Jenny Harmatys (Grayslake Central High School). Debbie Lojktz (Joliet West High School) awarded them with New Teacher Bags.
Gerry announced the Tri Physics meeting at Elmhurst College, Wednesday, January 17 where the Harald Jensen Award winner will be announced. Gerry explained that Harald had been a faculty at Lake Forest College and this year his widow asked to have the award presented at the Lake Forest College meeting.
Ann Brandon (Joliet Junior High School) announced that the bridge contest will be on February 15th and noted that it was on a Thursday this year. Nate Unterman (Glenbrook North High School) announced the days for Physics Day at Great America May 10 – 11.
We sang ‘Happy (50th) Birthday’ to Bill Blunk and another ‘Happy Birthday’ to Gerry Lietz.
Mike
McIntosh (Whitney Young High
School) made
a box to contain two speakers in tandem from an old Pasco box. The
speakers he
recovered from the trash. Mike connected the speakers to separate
signal
generators and showed how slight differences in frequencies generated
audible
beats. Then he raised the frequencies to shorten the wavelength of the
emitted
sound and rotated the speaker box to show how the speakers produced
spacial
zones of interference. Gerry reminded us of Tom Senior’s favorite
source of
cheep speakers, All Electronics at http://www.allelectronics.com/.
Bill Blunk (Joliet
Junior High
School - retired) reminded us of the demonstration exciting resonance
modes on
a metal bar. He excited the resonance by stroking the bar with his
rosined
finger. He then rotated the bar to show the resonance nodes and
antinodes. His
favorite use is to walk across the front of the room while holding the
bar 
horizontally
letting us hear the interference zones pass by.
Mike proudly pointed out that the Chicago Public School System has produced two female black astronauts, Dr. Mae C. Jemison (a student of Roy Coleman at Morgan Park High School, and now Joan Higginbotham who graduated from Whitney Young in 1982. Joan was to be on the latest NASA shuttle launch Dec 7. Mike is on the committee to redesign the AP Physics course. They are thinking of expanding the AP Physics B to a two-year course and he is looking for feedback.
Martha Lietz (Niles West High School) just started to use her (Vernier or Pasco) force plate. She had her students take the plate and Lab Pro data-collecting interface to a nearby elevator. She showed us how to set up the Lab Pro remote data collector. She asked several people to go to the elevator. Anne Brandon and Rich DeThorbne volunteered. They took the remote on the elevator to the fifth floor and back. When they returned and Martha downloaded their data and displayed a plot of the force as a function of time. We could see the increase and decrease of the force as the elevator started to go up and when it stopped at the fifth floor. Martha passed out a sheet with data she obtained at her school. She showed us a plot of the acceleration she had obtained from the data. She was able to integrate the acceleration with the software over the 2 seconds in which it occurred and obtained a speed of about 3 meters per second. She also integrated the velocity plot to obtain a change of position. She compared the data with an analysis assuming uniform acceleration with nice agreement. The position data also agreed with the distance between floors.
Eileen
Wild (retired) was shopping at
Jewel and found a set of
standard size Christmas tree lights that were LED’s and wanted to see
how they
compare in brightness to the traditional incandescent lights. They also
come in
mini-light strings. Gerry Lietz reminded us that for the incandescent
lights
95% of the energy given off as heat. Eileen confirmed that the
incandescent
lights gave off a lot of heat, which was a possible fire hazard if you
left the
lights on for a long time. Eileen had paid $5 for one string of 25 LED
lights
and calculated that one might use 7 strings to adorn a typical tree.
John
Milton brought out a Killa-wattmeter that plug into an outlet and has
an AC
socket into which one could plug a standard AC device. The meter would
then measure
the 
power
consumed by the device. He plugged the LED string and
measured one Watt at 0.01 Amps. The standard string used 37 Watts at a
half
Amp. Wow! More light for less with long lasting LED’s! and safer to
operate?
Thanks Eileen.
She also purchased a new flashlight similar to the one we saw at a previous meeting that charged by induction by shaking a permanent magnet through a coil. This one had a hand crank generator. Eileen was impressed with the high intensity of the white light LED which was clearly more intense than an ordinary flashlight. She got her flashlight at Fields in Oak Grove for $5 but also saw them in the Sharper Image catalog. The LED light should last a very long time.
Tom Senior (New Trier High School) took a standard refrigerator magnet and snipped it into small pieces such that each piece was about a quarter millimeter square, small enough to contain a single pole face. Refrigerator magnets usually have strips of alternating north and south poles on the side facing the refrigerator. He placed them in a Petri dish on the stage of an overhead projector inside the coil of wire that was attached to a Variac. As Tom turned up the voltage on the coil the magnet pieces began to jiggle around like atoms of an ideal gas. If he turned the voltage off gradually the magnets would cluster into groups like condensing atoms. If he turned the voltage off quickly they would not form clusters.
Tom used a small wedge to tilt the Petri dish and
we could
see the density of the jiggling magnets increased toward the lower side
of the
container. Tom liked this to the increased density of air lower in the
atmosphere due to the weight of the air above. This prompted a
discussion 
about
the relative spacing of atoms in each of the states of matter
that constitute solids, liquids and gasses. Nate Unterman (Glenbrook North High School) related
the common
misconception that atoms in a liquid are merely spaced out more than
those of a
solid. In fact while less dense than a solid due to more open spaces
among atoms,
the atoms in a liquid state still maintain contact with nearby atoms
and thus
are incompressible in first order. John Milton suggested adding a
larger object
to see if it would be jostled such as grass seed floating in a liquid
revealed
Brownian motion. We also brought up the hidden hazards of working with
a Variac
whose terminals may float at 110 volts even if the voltage difference
between
terminals is zero. Newer Variacs have a grounding ”third” contact.
Dan Cahill (Grayslake Central High School) had found a web site for applets on the internet. He brought up several of his favorites from the National Taiwan Normal University http://www.phy.ntnu.edu.tw/ntnujava/index.php. One simulator (Hit the links for Easy java simulations, E&M, and finally Particles and Walls.) allows you to draw an enclosed space and place charges (up to 500 particles) within the space. It then calculates the forces that would be present on each charge and calculates how they would respond. Several interesting things happened. Charges would always move out and accumulate along the walls verifying the fact that charges move to the outside of a conductor. Even more subtly the charges would gather in corners confirming the fact that corners have greater fields. There were many other neat features in the applet.
Another applet simulates an RC circuit (follow links to Electromagnetics and RC circuits). It shows the voltages across each part of the circuit and plots the change of voltage dynamically as a function of time. You can adjust values of initial voltage conditions and then run the simulation to can get values for conditions of charging and discharging. Lastly he pulled up a Kepler’s Law applet (in the upper menu hit Dynamics and then Kepler’s Laws) that, among other things, illustrates the 2nd Law of equal areas swept out in equal times. He found this simulation a lot easier to use than drawing many diagrams.
Nate Unterman (Glenbrook North High School) showed us a toy with two balls each attached to the end of strings joined at the other end at a handle. Pete Insley had them as his giveaway at a past ISPP meeting at Columbia College. The idea was to get the two balls rotating in opposite directions and sustain the motion by moving the handle. It requires some dexterity to synchronize both motions.
It was now time for the free giveaway. Gerry
Lietz (DePaul University) showed
us a piece of conducting
paper upon which he had painted a circle with conducting paint. In the
center
of the 
circle
he painted a dot. He used Pasco conducting ink
($22). A similar product was available at Tri State Electronics. He
explained
that one could use a voltmeter and probe to map out the potentials
generated by
attaching a voltage source between the circle and the central dot. This
is how
the experiment is done usually. Gerry had an interesting twist to show
us. He
had read in a The Physics Teacher article
in the October 2006 issue, pp 470 - 472, how the authors, Daniel
Ludwigsen and
Gregory Hassold, had constructed a probe that consisted of a small wood
block
in which he had driven through two three inch upholstery needles (the
kind with
an eyelet at one end). He spaced them a distance of a one centimeter
apart.
Then he connected the two needles to the terminals of a voltmeter which
measured the voltage difference over the distance of a centimeter. He
placed
the probe needles onto the conducting paper and rotated the probe to
get the
largest voltage reading. Gerry explained that this is effectively gave
a direct
measure of both the magnitude and direction of the electric field E
since E is
defined as -DV/Ds. Gerry showed us some data he
had taken
that demonstrated the inverse r dependence of E in this geometry which
was akin
to a coaxial cable. Neat device! Gerry had made a bunch of probes as
our free
giveaway. He also had made up a conducting sheet with a painted circle
to go
with the probe. Gerry also had some books to giver away as well as a
Pasco
power supply which he gave to a lucky random number holder.
Since
this was the
last meeting that Gerry would be attending as a host before his
retirement John
Milton presented him with a plaque with pictures taken from past
meetings. John
and Martha had a cake commemorating the occasion.
Submitted by Art Schmidt
For any information regarding ISPP contact Gerry Lietz at DePaul University, Physics Department, 2219 N. Kenmore Chi. IL 60614 phone: 773-325-7333 e-mail glietz@depaul.edu. ISPP home page: http://condor.depaul.edu/~glietz/ispp/ispp.html
DIRECTIONS TO ELMHURST COLLEGE
By way of Interstate 290 (Eisenhower Expressway)
Exit at St. Charles Road, just west of I-294
Travel West on St. Charles, past York Road, to Prospect Avenue
Turn right onto Prospect for two long blocks, past the front of the campus on your left, to Alexander Boulevard
Turn left, then left again, into the main parking lot
By way of Interstate 294 (Tri-State Toll way)
From the south, exit at I-290
From the north, exit at I-290 West, then exit again immediately at Illinois Route 64 West (North Avenue)
Follow North Avenue about a half-mile, past York Road, to Maple Avenue
Turn left. Follow Maple
Avenue another
half-mile, two blocks past railroad tracks to Alexander Boulevard.
(Maple
Avenue becomes Prospect Avenue after the tracks)
Turn right, then left, into the main parking lot
North Avenue
By way of Interstate 88
(East-West Toll way)
Third St.
Exit at York Road, just west
of I-294. (Take ramp marked I-294
South)
Travel north on York for about two-and-a-half miles to St. Charles Road
Turn left on St. Charles to Prospect Avenue
Turn right on Prospect for two long blocks, past the front of the campus to your left, to Alexander Boulevard
St. Charles Rd.
Turn left, then left again,
into the main parking lot
Meet Here
