OUR NEXT MEETING. . .
                                                                       . . . is at Northeastern Illinois University
                                                                                          Thursday
                                                                                          February 7

6:30 - 9:00 p.m.

We will meet in room S209 (second floor), where we will have activities, munchies, and informal interaction until about 7 -- then we will move down to lecture hall 1 (aka S101), and start the (very slightly) more formal portion of the meeting at 7:05 pm

IMPORTANT PARKING INFORMATION WHEN YOU PARK AT NEIU, YOU WILL NEED TO PICK UP A PARKING TAG .  GET A TAG IN THE MEETING ROOM AND RETURN TO YOUR CAR TO HANG THE TAG FROM THE REAR VIEW MIRROR.

Click here for directions and a map.

AT OUR LAST MEETING…(the 24th annual Tri-Physics Meeting)…
…at Elmhurst College, after pizza, soft drinks and conversation, Earl Swallow welcomed us and told us that his colleague Mark Timko will be moving to Iowa in the near future. We will miss Mark’s support of ISPP. Earl reminded us that next year Elmhurst will host the 25th annual Tri-Physics Meeting, and promised there will be some special features.

A few announcements:   Paul Dolan (NEIU) gave us a website where we could find and download the Force Concept Inventory (FCI) and the Mechanics Baseline Test in several languages. You must use a school e-mail address. Go to http://modeling.asu.edu/ and scroll down to Research % Evaluation.

Future Meetings and Events

Physics Northwest	Rolling Meadows H.S.	Feb 19 (Tue)	Katie Page
	Wheeling H.S.	March 5 (Wed)	Raeghan Graessle
ISPP	Northestern Illinois University	Frb 7 (Thu)	Paul Dolan
	Chicago State University	Mar 12 (Wed)	Mel Sabella
	Lake Forest College	Apr 1 (Tue)	Scott Schappe/Nathan Mueggenburg
	Northwestern University	May 5 (Mon)	Art Schmidt
	MSI or Columbia College	June 3 or 10 (Tue)	Ruth Goehmann or Pete Insley
CSAAPT	Harper College	Mar 15 (Sat)	Invited Speaker: Randy Knight
Physics Day	Great America	May 8 (Thu)	AnnBrandon/Roy Coleman

There is an Amusement Park Physics Workshop at Argonne National Laboratory, Monday, Feb 18, 8:30-1:00. Cost is $65.
Contact  igordon@anl.gov.

We welcomed several new teachers. Nate Unterman (Glenbrook North High School.) asked for information about schools doing Physics First as part of a major revamping of their science curriculum. numterman@newton.dep.anl.gov.

Roy Coleman (Morgan Park H. S., retired) continued a discussion he started at the De Paul meeting about the flight of a football. This time he brought a javelin and asked the same question about its trajectory. There was an interesting exchange of ideas about the role of spin, torque, air resistance and turbulence. [Editor’s note: After the meeting, Mark Timko brought out a copy of Football Physics by Timothy Gay (available from AAPT). In Chapter 6 there is a detailed treatment of the football trajectory problem. See also http://footballphysics.utk.edu/ from the University of Tennessee. Most of the links on Google under “football trajectory” are to what we in the States call soccer.]

Dave Torpe showed us a neat approach to demonstrating friction. [Dave is student teaching at Conant High School and will be seeking a teaching position next year. (DaveTorpe@gmail.com)] He had two soft cover books a little more than an inch thick. He laid them flat and interleaved them, like shuffling a deck of cards, he said. Then he grasped them by the binding ends and tried to pull them apart, with no success. To quiet the skeptics, he had Paul Dolan pull on one book and he pulled on the other, again without success. Then he held the books vertically and was able to pull them apart with ease. Roy Coleman suggested using books from the non-friction section of the library. Ouch!

Joe Liaw and Ryan Dunn (Hinsdale Central High School) passed out a student instruction manual for Tracker, free motion analysis software (http://www.cabrillo.edu/~dbrown/tracker/). Ryan, who wrote the manual, is currently a student teacher (RDunn@niu.edu). Joe juggled some balls and Ryan used a camera that can take short video clips (QuickTime). They then showed us just a few of the many video analysis features of the software.

Steve Zownorega (Zownorega@gmail.com) (student teaching at Wheaton Warrenville South High School under Jim Stankevitz) gave us a Program Guide/Lesson Ideas handout to use with the Electric Field Hockey, a PhET program available from the University of Colorado at Boulder (http://phet.colorado.edu/new/index.php). A charged puck (+ or −) has to move through a maze to a goal. The user can place charges at various locations and use the electric force between the charges and the puck to “steer” the puck into the goal. There are three levels of difficulty. Steve asks students to describe their strategy and the models they used to develop it. Electric field lines can be displayed to help the student visualize how the forces act.

Martha Lietz (Niles West High School) asks her students to consider the equivalent spring constant and the period of simple harmonic motion for two springs connected in series and in parallel, both with equal and unequal force constants. She outlined how she helps students work their way through the analysis of the various combinations. But then of course, she set up these combinations and showed us how she and her students measure the spring constants and compare them with predictions. She raised a question we may not have considered: What happens when two unlike springs in parallel are connected by a string or a string wound through a pulley? We saw what happened and discussed how to analyze this system. Bob Froelich (Glenbrook North High School) brought a $5 interferometer. It uses a Radio Shack silicon photocell mounted on a wood support with leveling screw and covered by a microscope slide. A HeNe laser is directed to the photocell and the reflected beam interferes with the incident beam to set up a standing wave. Movement (e.g., of the table on which the system is mounted) changes the interference pattern and the output of the photocell, connected through an amplifier to a speaker. Bob gave us a handout with good  drawings and photos of the setup and entertained us with a variety of sounds, such as moving the teeth of a comb through the beam. There was some discussion about how the standing wave is set up. (Editor’s note: a plausible explanation can be found at http://amasci.com/amateur/lasqueal.html.)

The winner of this year’s Harald Jensen Award was announced by Ann Brandon and Debbie Lojkutz. It will be presented to Bruce Medic from Glenbard West High School on April 1 at the Lake Forest College meeting. Congratulations, Bruce.

Scott Beutlich (Crystal Lake High School) and Josh Norton (Cary-Grove High School) set up a Ping Pong Cannon, Their handout included an equipment list, a building guide, directions for use, and calculations to estimate the speed and energy of the ball. They set it up and fired a ping pong ball into an empty soda can, with noisy and impressive results. Scott showed us a “Ruben’s Tube” made out of a square section of drainpipe. There are movies of this standing wave flame phenomenon on U-Tube. A few people had set this up or seen this set up with an air track.

Mark Ailes (Addison Trail High School) held up a glass jar nearly filled with what looked like chili beans. A metal ball was resting on the beams. Mark shook the jar and as he did the ball disappeared and a lighter ball cam to the surface. Is there something about buoyancy going on here?

Arlyn Van Ek (Illiana Christian High School) set up what looked like a vortex tube demo that many of us had seen before. But he asked; What would happen to small bits of material floating in the liquid as the vortex developed? He then showed us what would happen. The floating particles (cork) were drawn into the vortex and were transported into the lower soda bottle. Then he passed out material (“Lake Peigneur: The Swirling Vortex of Doom”) about a large scale vortex that occurred in Louisiana in 1980. Hid handout came from a website: http://www.damninteresting.com.   John Lewis (Glenbrook South High School) fixed 35 mm film cans filled with sand (with duct tape closing one end) near the ends of a rotating platform of radius ~.2 m. After an elaborate introduction, and properly attired with hunting hat and safety glasses, he fired a BB from a Daisy Red Rider BB gun into one of the film cans and the system rotated rather slowly about 1/3 rad/s, he said). He took us through a neat series of approximations, equating the initial angular momentum, mvr, with the angular momentum after the inelastic collision of the BB with the film can, Iω. He also gave us m (about .03 g), I (.02 kgm2). This yielded a BB speed of about 160 m/s, consistent with the manufacturer’s figure of 600 ft/s.

Paul Dolan (see picture above) used a Zircon Stud Finder to try to locate studs in the wall of the room, without much success – there are probably no wood laths in those walls. In an older house with fairly narrow wood (not wire) laths the stud finder detects the change in dielectric constant as the instrument is swept along the wall and encounters a stud. Paul explained that the device is a special kind of parallel plate capacitor with one plate in the middle and the other split into two connected pieces

Paul told us that “salvage” people who came to look at the aftermath of a water break in his house used what he thought was a similar instrument to measure moisture in the wall. It had what looked like two electrical contacts on the side that was in contact with the wall, and it works with wire lath .Ann Brandon thought it was measuring conductivity and Larry Alofs suggested it was sensitive to the polarity of various kinds of molecules.

Ann Brandon gave us some scary statistics about the gap between future need and supply of high school physics teachers in Illinois. She gave us some brochures for counselors, teachers, and students to encourage students to consider a career in science teaching. She was the committee organized by the Illinois Section of AAPT, in cooperation with the Illinois Association of Chemistry Teachers, the Illinois Science Teachers Association, and the Chicago Section of AAPT. Ann encouraged us to get these into the hands of counselors and students.

We thanked our Elmhurst hosts and were able to leave, for a change, without scraping snow off our cars!

Reported by John Milton

To get to Northeastern Illinois University From the expressway: Coming from the northwest or from the south on the Kennedy, exit at either Kimball or Pulaski going north, and follow that to Bryn Mawr Avenue. From  Kimball turn west. From Pulaski  turn east. Coming from the north on the Edens exit at Peterson & take that to Pulaski, turn south on Pulaski to Bryn Mawr (just after the nature center).Turn east onto Bryn Mawr. Park in the Level II lots or the Level II area in the garage (which is labeled "PF" on the map – Parking Facility) By CTA Take the Brown Line to the end (Lawrence & Kimball), and take the Kimball (#82) bus north about 1 mile to Catalpa, and walk 2 blocks east to campus) -- or take the Blue Line to Foster (Jefferson Park), and take the Foster bus east to Central Park -- the bus stops at the south end of campus (just beyond the PE complex).