07 September 1999:  Fred Schaal [Lane Tech HS]
He showed his new bike, with the spokes off center. Why is this true only on the rear wheel? The back wheel had the spokes offset, and not on the center of the "U" for the tire. It was mentioned that some bikes have three spoke wheels, and  it was said to be only for racing. It was pointed out that police bikes have these wheels

26 October 1999: Bill Colson (Morgan Park HS)
told us about the Intel Virtual Microscope [http://micro.magnet.fsu.edu/optics/intelplay/index.html], and then about New Scientist Magazine with science questions and answers [http://www.newscientist.com/ and click 'lastword']. And then we learned about the Biltmore Stick for measuring tree heights [http://forestry.about.com/b/a/081153.htm]. Neat!

11 April 2000: Earl Zwicker (IIT Physics, ret)
showed us a chunk of # 3 coaxial power cable from Com Ed. It was installed about 3 - 4 ft underground without need to dig a trench, a few hundred feet at a time. How is this done? Relatively recent technology. Photos at a future meeting.

02 May 2000: Roy Coleman (Morgan Park HS)
held up the power line cable that Earl Zwicker had discussed with us last meeting, and then he described a house wiring problem that he was involved with that had occurred many years ago. Strange things happened: The dog would do a flying leap over the threshold when coming back into the house, which necessitated his continuing on down the basement stairs, then back upstairs to get in. Why? When some lights were turned on, other lights would become dim. Why? A water pipe in the basement corroded and had to be replaced, and the problems became worsened. An electrician called in to find the problem gave up after 2-3 hours, shaking his head, and never sent a bill. Roy drew a circuit diagram on the board showing a step-down power transformer and the low-voltage secondary with center-tap to ground and its + and - 120 V/AC ends going to serve the house power. What they finally discovered could be seen only from a second-story bedroom window. The ground wire from the secondary of the step-down transformer passed through a tree next to the house, and it had broken. Thus, the entire house wiring was "floating" with respect to ground, and any connections to the grounded power transformer primary were being made through grounded water pipes, etc. Com Ed was called, and they got out there and fixed it in record time once the problem and its consequences were made clear. Most interesting!

02 May 2000: Larry Alofs (Kenwood HS)
gave us a handout from Science News, April 1, 2000, describing the new golden dollar [http://www.usmint.gov/mint_programs/nativeAmerican/] bearing the likeness of Sacagawea, "...the young Shoshone woman who guided Lewis and Clark..." The metallurgy involved was tricky; the new coin will not require the retooling of vending machines. The make-up of other US coins was listed out on the same page. A most useful reference for physics teachers. Thanks, Larry!

30 January 2001 Fred Schaal (Lane Tech HS)
asked the following questions:

1. How do Modern Construction Cranes maintain their balance?
2. How are they raised into their positions of operation?  

From the discussion that followed, these ideas emerged.  The cranes have the following structure:

The beam pivots horizontally around the vertical shaft, and the hook is used to lift a load to the desired point. There is an internal counter weight that moves horizontally along the beam, which is used to balance the load.  These cranes are assembled on the ground, with a short shaft to support the beam and horizontal members.  The system is carefully balanced on that short shaft.  The system is then raised hydraulically from the ground, and the shaft is repeatedly extended by adding sections of about 3 meters [10 feet] in height after each raising.  These systems are securely anchored to the ground, and are considered to be much more stable than the traditional "leaning cranes".

30 January 2001 Porter Johnson [IIT] mentioned that such cranes have been used in Europe for more than 20 years, and are in common use here.  During a trip to Berlin in 1995, he noted that the infamous Berlin Wall had been almost completely removed, but that its path was marked by these Modern Construction Cranes.  Also, he described an automated system for taking images of a construction site and storing them on a computer.  The images could then be played back in succession, showing the progress of construction on the site, as well as the periods of delay.  It is a fairly simple exercise in computer wizardry to develop this "permanent record" of the construction process, with the goal of improving efficiency and thereby reducing costs. 

28 September 2004:Fred Schaal [Lane Tech HS,  Mathematics]           Afterburner Bike Rides 
Fred  had just taken advantage of 30 knot winds to the South, in riding his bike on the bike path along Lake Michigan, on the way to our class.  A month ago he encountered a serious sand blizzard on that route because of the high winds -- but not this time!  Fred showed off his flashing red LED bike tail light with a "bulldog clip".  Also, he showed a  flashing headlight that contained LEDs.  Don Kanner mentioned that the Inch Gear  on a bicycle is defined as the diameter of the drive wheel (in inches) multiplied by the mechanical advantage of the gearing system.  Believe it or not! For details see the website The Bicycle Gear: How It Works for us: http://bicycletutor.com/gear-shifting/. Fred also mentioned the full moon tonight, with the summer triangle (and little else) visible in the sky.  Thanks, and enjoy the monsters, Fred.

23 November 2004: Bill Blunk [Joliet Central HS, retired]           How Smooth is Smooth? 
Bill  passed around the following information, which was excerpted from instructions for Brownells Flex Hone System provided by Brownell Corporation http://www.brownells.com/ .

"How Smooth is Smooth?
We often use the phrase 'as smooth as glass', yet glass is not really very smooth! In fact, it's quite rough. To prove this point, perform the following simple experiment. Select a piece of glass such as a window pane glass top or even a mirror. Using the forefinger and middle finger, very lightly slide your finger across the surface of the glass. it will feel smooth. Now, remove the cellophane wrapper and repeat the performance."

07 December 2004: Bill Blunk [Joliet Central, retired and getting "mellow"]           Tactile Magnifier: Cellophane
Bill reminded us of these observations  made at the last MP SMILE meeting [mp112304.html] , concerning the apparent "bumpiness" of a glass surface when rubbed:

The manufacturer of the cleaner had claimed that bumpiness felt through the cellophane is caused by surface imperfections in the material.  Although these results seemed to confirm that point, we looked for other explanations:  imperfections in the cellophane itself, oil on our fingers, waxy yellow buildup, ...  Bill then told us that his description of the experiment had not been complete.  Actually he had very carefully wiped the telescope lens beforehand.  He posed an explanation involving surface dust on the lens.  To verify this point, he smacked two blackboard chalk erasers together, thereby scattering some chalk dust on the glass lens surface.  It felt bumpy after this -- just like ordinary glass. Aha!

Why, then, does cellophane enable us to feel the "bumpiness" of surface dust? Perhaps the dust serves as a sort of "tent pole" to raise the cellophane around it, creating a larger bump for our sense of touch to detect.  Research instruments such as the Scanning  Electron Microscope (SEM) and Scanning Tunneling Microscope (STM) [see http://www.mos.org/sln/sem/ and http://physics.nist.gov/GenInt/STM/stm.html] are used to create images of sub-microscopic surface irregularities --- even down to the atomic level! 

 The role of the non-uniform response of nerve endings in the fingers and elsewhere to tactile sensations was also discussed.  It is a fact that  you cannot tickle yourself.  Being tickled  requires being surprised by another person.  In other words, it's more psychological than physical.  Then, how can ever we trust our sense of touch? And yet, we must!

Very thought provoking, Bill!

14 December 2004: Paul Fraccaro [Joliet Central HS, math & science]           Best Paper Size? 
Paul showed a geometrical construction that permits the precise alteration of an ordinary sheet of notebook paper (width W = 216 mm (8.5")  by length L = 279 mm (11") into one of the same length, with W = L / Ö2  = 198 mm. According to Paul, this paper corresponds to the international standard scale.  Furthermore, he claims that it is the ideal size for making paper airplanes. Here is the construction:

1. Fold side AB (about angle ABD) onto side BD, and mark the point E on BD where A lies.  The length BE will thus be equal to AB.
2. Unfold the paper.
3. Draw the line AE, and fold side AC (about angle CAE) so that it lies along the line AE.  Mark the point on line AE that corresponds to the end of line AC; call it F
4. Draw a line (GFH) parallel to side BD, passing though point F.
5. Cut off the paper along the line GFH.
6. Stop; you're finished!

Standard A4 paper sheets, used for letters, printers, and copying machines, are approximately 210 mm wide by 297 mm long, corresponding to an area of about 1/16 square meters.  Note that 297 / 210 ~ Ö2 = 1.414.

For more information on International Standard Paper Sizes, see the website http://www.cl.cam.ac.uk/~mgk25/iso-paper.html, from which the following is abstracted:

"... In the ISO paper size system, the height-to-width ratio of all pages is the square root of two (1.4142 : 1). This aspect ratio is especially convenient for a paper size. If you put two such pages next to each other, or equivalently cut one parallel to its shorter side into two equal pieces, then the resulting page will have again the same width/height ratio.

ISO 216 defines the A series of paper sizes based on these simple principles:

• The height divided by the width of all formats is the square root of two (1.4142).
• Format A0 has an area of one square meter.
• Format A1 is A0 cut into two equal pieces. In other words, the height of A1 is the width of A0 and the width of A1 is half the height of A0.
• All smaller A series formats are defined in the same way. If you cut format An parallel to its shorter side into two equal pieces of paper, these will have format A(n+1).
• The standardized height and width of the paper formats is a rounded number of millimeters ..."

For instructions on making various types of paper airplanes see Alex's Paper Airplane website http://www.paperairplanes.co.uk/.

Does this really give us the best gliders? Very interesting, Paul!

25 January 2005: Walter McDonald [CPS Substitute Teacher]           Interference of a Digital Clock
Walter obtained a new laptop computer, along with a router for wireless operation on the internet.  When he plugged an old digital clock into the same receptacle, he noticed that the digital clock began to run erratically and quite fast.  Why?  One possibility was that the digital clock, which is supposed to count the Voltage peaks of 60 Hz AC current, was also counting small Voltage spikes, as well.  The clock chip might be interpreting a voltage fluctuation as an AC voltage maximum, and including it in the time count.  Early digital clocks would sometimes respond to such spurious signals, in the more recent versions this usually does not occur.  Unfortunately, the clock soon stopped working, so that it would be difficult to study the problem now.  What do you think about this?  Could the wireless circuitry be involved?

That's quite a puzzle!  Thanks, Walter.

08 March 2005: Leticia Rodriguez [Peck Elementary School]              Ceragem Thermal Acupuncture Massager
Leticia has been using a thermal massage bed, which is described on the Ceragem website:  http://www.ceragem.com/. The following is excerpted from that website:

What is Ceragem?
CERAGEM is a thermal massager that helps soothe body aches and pains associated with daily stress, pressure, and bad posture. It combines the benefits of alternative medicine derived from traditional Eastern medicine with advanced technology to provide the most effective healing and relaxation. Ceragem is easy to use and highly effective, as proven by the positive feedbacks we received from our customers. Ceragem is available for free trial at our distribution centers.

The device consists of a bed with rollers for spinal alignment, with an IR light source to stimulate circulation.  Leticia asked that we each go to test this device (six times, without cost) to assess its effects on our health and happiness, at the following location:

5756 West Belmont Avenue, Chicago IL
(773) 205-1020

10 May 2005: Leticia Rodriguez [Peck Elementary School]             Evaluation of CERAGEM Thermal Bed
As outlined at the SMILE meeting of 08 March 2005, mp030805.html, Leticia evaluated the claims for this Acupressure Thermal Bed with Jade rollers, based upon her own experience this spring.  Here is her evaluation:

1. Massage therapy is a standard means of promoting healing and improving muscle tone.
2. Deep infra-red radiation is likely to produce physical symptoms similar to "prickly heat" obtained in the summer sun.
3. Any means of improving muscle tone and promoting exercise --- particularly aerobic exercises lasting over 30 minutes, will produce significant cardiovascular benefits.
4. Any claims of "detoxification of the body" are rather far-fetched, difficult to believe, and challenging to prove. Simply put, infra-red radiation in the body does not seem to destroy toxins in the system.

Thanks, Leticia.

01 November 2005: John Scavo (Kelly HS)             Hybrid Vehicles and Digital Cameras
John shared two articles (handout) which illustrate how he uses research to decide what kind of things to buy. One article points out the great disparity between the actual gas mileage achieved by hybrid cars compared to the estimated mileages. When different makes or brands of cars are considered, hybrids have among the greatest disparity between the two numbers. Charlotte had much better results with her Toyota Prius than reported in the article. Others shared even better results than Charlotte with "gasoline only" cars (eg, Saab Sonett). A second article talked about digital cameras and mentioned that the circuitry for almost all modern digitals comes from Kodak. Thanks, John.

24 January 2006: Chris Etapa (Gunsalaus Academy)             Get a grip
Chris brought a group of three "artificial arms" that had been made by students in the Get a Grip program, in which Chris has participated the last two years. It is sponsored by the Bioengineering Departments at UIC and Northwestern U. The hypothetical background is that the artificial arms are made for a farmer and have to be made from everyday materials (supplied in a box to each team along with a screwdriver and hammer as the sole tools), because the farmer lives in a poor country. They are supposed to be designed so that the farmer can return to his farming tasks. The arms are scored on both functionality (picking up and carrying a bucket of water, picking up olives) and low cost. The following statement of the Engineering Challenge appears on their web page:

"Students are faced with one of two challenges that help them learn concepts of engineering. One group focuses on designing a prosthesis that will help people in third-world countries to pick up and move a bucket of water. The other focuses on designing a prosthesis that will allow people in third-world countries pick up and eat grapes without damaging them. Prosthesis will be built with materials from local hardware and department stores that mimic what is available in third-world countries. Their challenge is to use these materials to build suitable prototypes. They test them in the classroom and report their findings at the end of the program."