Our next meeting...
Monday, May 5, 6:30-8:30 P.M.
Click here for a map.
| Future
Meetings |
||
| June 10 (T) |
Museum of Science and Industry |
Ruth Goehmann |
| July 19-23 |
http://www.aapt.org/ |
At our last
meeting...
| …at Lake Forest College on April 1 (no
fooling), Scott Schappe,
department chair, welcomed us and told us that Mike Kash is on sabbatical at Texas
A&M. Three other Lake Forest faculty were on hand: Nathan Mueggenburg, Bailey Donnally, and Tung Jeong (the latter two now
retired). Scott introduced Tung, who proceeded to “enlighten” us about
the phenomenon of interference using a laser and a very small concave
mirror mounted on a rod. He produced several two source interference
patterns and modeled them using overlapping transparencies of
concentric circles. We each got one of the mirrors as the evening’s
giveaway, along with an explanatory handout. |
 |
| Gerry
Lietz made some announcements and reminded us to think about a
recipient for the John Rush Award..
Contact Bill Blunk (billb9439@comcast.net) if you want to
suggest a candidate. Congratulations were offered to Tom Senior (New Trier High School)
for receiving a Distinguished Service award from AAPT (see the April Physics Teacher). Ann Brandon and Debbie Lojkutz presented the Harald Jensen Award (the famous
Jensen Bar), a copy of Robert Adair’s Physics
of Baseball, and the cost of a half year membership in AAPT to Bruce Medic (Glenbard West High
School). Ann told us that a letter and a donation had been received
from Harald’s daughter. Ann recalled the earliest days of ISPP
while some slides of Harald in action were shown. |
 |
Gerry passed around a cylindrical glass rod
through which one could see a message in red and black letters. He used
this to give middle school teachers an example of using a
phenomenological approach to hypothesis formation by their students –
why is one word upside down and the other not? He told us we could find
many good ideas by looking at IIT SMILE on Google. Gerry then showed us
Harald’s approach to deriving the Pythagorean theorem. Next, we saw a
slide of Harald demonstrating a conical pendulum. Scott brought out the
very device and demonstrated it for us. We saw another slide of Harald
demonstrating electromagnetic induction with a magnet, coil and large
galvanometer.
 |
 |
 |
Roy Coleman
(Morgan Park High School, retired) recalled another challenge from
Harald – to find the radius of curvature of a 2 meter stick balanced at
the middle. Harald showed that the period of an oscillating ring is the
same as a simple pendulum with length equal to the diameter of the
ring. He then showed that the period is the same for any sector of the
circle.
Dan Cahill (Grayslake Central
High School) connected a length of 30 gauge nichrome wire to a power
supply set to 0.5 V and hung a second heavier piece (about 4 times the
diameter of the thinner wire) below it. He first showed that the
current increased as the length of the wire connected to the supply
decreased. Then he showed that since the area ratio of the two was
about 16/1, the current ratio for equal lengths of wire was about 1/16.
Karlene Joseph (Lane Tech High
School) told us that she has a deaf student who comes to class with a
signer. The student has a cochlear implant that does enable her to hear
the high pitch of a wine glass rubbed with a finger. Karlene looked for
ways to get some ideas about sound across to this student. She use Real
Time Analyzer software to find and play the resonant frequencies of
open and closed tubes of different lengths, and the frequency
components of different vowels sung at the same pitch.
 |
 |
| Art
Schmidt (Northwestern University) said a visitor from U of I
had spoken at NU about the physics of baseball and referred to the
liveliness of the ball. Art used a tennis racket to demonstrate some of
the differences between “happy” and “sad” balls that many of us have
used. He used both the smaller and larger versions of these. There was
a small difference in rebound height from a horizontal racket, much
less that the difference of interaction of the balls with a table top. |
 |
Then he used a PASCO ball launcher to hit a cart
with each of the small balls. so we could think about momentum
transfer. It appeared that the happy ball, which bounced back more,
imparted more momentum to the cart. Art noted that the ball masses are
not quite equal. Then it was suggested that we compare the balls’
motions when they rolled down a ramp. The sad ball won by a small
margin. There were competing suggestions as to why this happened.
Finally, Art gave us a handout about a Northwestern web site that
describes much of NU’s research around the world.
| Bill
Shanks (Joliet, retired) brought a copy of “The Dangerous B Book
for Boys” and turned to page 16 for instructions on making a battery.
His consisted of layers of aluminum foil, thick paper toweling
saturated with a vinegar and salt solution, and quarters, His book
claimed that this battery could light an LED. He proceeded to connect a
red LED and it did light. He repeated this, using a green LED. After
some discussion of what was happening in this Voltaic cell, Bill let us
in on his April 1 secret – at the bottom of the pile there was a small
button battery! Eileen Wild (CPS, retired) told us of cosmology articles in Sky and Telescope and Scientific American about the early universe, and passed out cards with satellite representations that show “hot spots” where star formation was occurring. Come to Northwestern! Bring friends! |
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Reported by John Milton.
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
http://www.northwestern.edu/visiting/directions/index.html
