Kanner (Lane Tech,
Don projected an image of the instrument panel of a locomotive on the screen at the front of the class. He used the MSTS locomotive simulator, which can be run on a computer to teach physics in class. Two (brake) pressure gauges, a speedometer, a digital clock, a Train Status indicator, and a Force Gauge were visible. Don highly recommends the Print Screen™ software program on Windows™ to save images at time intervals from this (or any other) program to a folder of your choice. See also this URL: http://www.download.com/Print-Screen-Deluxe/3000-2094_4-10356546.html?tag=lst-0-2. In addition, see the (free, downloadable) Picasa2 Picture Editing Software: http://picasa.google.com/index.html. These screens then can be used as a data set to help with problems involving, for example, speed and distance versus time, for uniform linear acceleration, variable acceleration, and circular motion. In particular a decrease in acceleration for a certain locomotive automatically occurs at a speed of 45 m/s, with a corresponding decrease in force, explained by Newton's Second Law. This locomotive is programmed to accelerate more quickly at low speed, and less quickly at high speed, to stay on schedule. Good stuff! Thanks, Don.
Betty Roombos (Gordon Tech HS,
Explore, Plan, and ACT
Betty recently proctored a pre-ACT Plan Test [http://www.act.org/plan/] -- a practice test for the ACT that is often taken by 10th graders. Biology, weathering, conservation of mass and water, wave-particle model with photoelectric effect, and centripetal force were among the topics covered. Betty felt that this sophomore level test included topics beyond what the sophomores should be expected to know. She asked whether the Plan Test was thus appropriate for practice. Another concern was that the students were not given enough time to reason out the information in the test -- which was given via complicated charts and graphs. Good questions! Thanks, Betty.
Fred Schaal (Lane Tech HS,
RR on the GD (RailRoading on the Great
Fred handed out a sheet he had gotten from a search engine of American Orient Express [http://american-orient-express-train.com/]. He saw the name on some train coaches last summer during his western train trip. These luxury train voyages run on AMTRAK routes; the 2006 schedule is given on this page: http://american-orient-express-train.com/trips.shtml.
Fred also asked why the full moon seems to hanging so low in the sky. For additional information see the NASA web page Summer Moon Illusion: http://science.nasa.gov/headlines/y2005/20jun_moonillusion.htm. Thanks, Fred.
Brandon (Retired, Joliet
Halloween Math + Straw Stuff
Ann had a roll of ticker tape to illustrate Halloween Math -- specifically to determine what one gets when one divides the circumference of a pumpkin by its diameter. As surrogates for pumpkins we used round plastic jar caps of various sizes. Pieces of ticker tape the length of the circumference and the length of the diameter were measured and torn from the ticker tape roll. Each person then had a diameter and a circumference for their "pumpkin". Ann attached a magnetized meter stick vertically to the blackboard, which was used to mark the distances for each person's ticker tape pieces. It also served as the Y-axis for a set of coordinates on the board. The length of each circumference was the Y-value and the length of each diameter the X-value for a point with coordinates (X,Y) -- one data point per person. This produced points that traced out a straight line, the slope of which was p, ie, the function which describes the line is Y = p X. That is, the circumference of a circle is p times its diameter: c = p d.
Ann also pointed out that with tape each student could tape his/her diameter strip on the X-axis, with the circumference strip taped at right angles starting at Y = 0 and the right end of the diameter strip, leaving the top of the circumference strip at the place where the corresponding point will be. Using the best fit, we calculated the slope of the line to be 64.3 cm / 20.5 cm = 3.1366! Pretty close to the real thing-- now let's eat some real Pumpkin p!
Ann then showed two old cardboard boxes filled with Swan paper straws (probably dating back to the 1970s). There are things you can do with paper straws that you cannot do with plastic straws. Paper straws are reportedly still available from a coffee supply company or at a Hard Rock Cafe™ . They can also be ordered from art supply catalogs, commonly used by art teachers in schools. She cut an inverted V into the flattened end of a straw, forming a double reed, like an oboe. Ann then blew continuously into the straw, producing an oboe-like sound. As she did this, she used scissors to cut successive pieces from the end of the straw. We heard the pitch of the sound getting higher -- usually, but not always.. Ann then showed how you can make smoke (which you may need for a demonstration with a LASER, etc) by lighting the end of the straw and letting it burn down a bit. Then she blew into the straw, causing the smoke to puff out of the lit end by squeezing the unlit end of the straw. Neat stuff, as always! Thanks, Ann.
Walter McDonald (VA and CPS substitute
Hidden Magic Coin
Walter handed out a sheet which contained directions for the hidden coin trick (from Hidden Tricks: Playthink #613 from the book 1001 Playthinks by Ivan Moscovich [see hs100405.html].Walter then, with Fred's help, performed the trick -- which worked perfectly!-- and which illustrated the mathematical concept of parity checking; see the Webopedia web page What is parity checking?: http://www.webopedia.com/TERM/P/parity_checking.html. Walter then discussed the role of parity in computer operation. It is used to check the accuracy of data sent from one computer to another.
Five coins were shaken and then scattered onto the table. Walter looked at them, and asked a volunteer to turn over any two coins, and then cover up any one coin from view. Walter then looked at the four coins in view, and told us that the hidden coin was "heads". We looked. He was right -- and we applauded Walter! Walter repeated this feat a second time, and he made us all curious to know how he did this. Marilynn Stone figured it out. You need at first to count the original number of heads and remember it. Then count the number of heads in the final configuration with one coin covered. When you then flip two coins, only the following three cases can occur:
|Initial||Final||Change in #Heads|
Dianna Uchida (Morgan Park HS,
Science Fair Projects
Dianna shared an article by Emilie Le Beau that appeared in Kid News: (11 October 2005, Chicago Tribune). It gave the following 10 tips for preparing science fair projects --- particularly for students who waited too long and were short on time:
Roy Coleman (Morgan
Air Gyroscope made from a Bowling Ball
In 1968 Roy took a course with Harald Jenson at Lake Forest College, which inspired him to build an air gyroscope [http://www.physics.umd.edu/lecdem/services/demos/demosd4/d4-10.htm] using a bowling ball. A bowling ball (with a metal rod about 10 cm long and 1 cm in diameter that was threaded radially into the ball) sits with its bottom half resting on a hemispherical plaster cast of itself and mounted at the top end of a metal cylinder. A vacuum cleaner is used to flow air into a tube leading to the bottom of the hemispherical plaster cast. Subsequently, when the ball is placed into the hemisphere, it is supported on a nearly frictionless film of air flowing between it and the plaster. Once the ball is rotated with the help of a hand, it continues to spin, and it precesses and nutates -- both are easily seen in the motion of the rod above the ball. Roy used this project for his Masters Thesis at Loyola University. Roy's description of this Bowling Ball Gyroscope appeared in the journal The Physics Teacher [http://scitation.aip.org/content/aapt/journal/tpt] in 1970. In a short ceremony -- and with our applause! -- he gave the apparatus to Debbie Lojkutz , who had used and broken this apparatus when she was Roy's student at Morgan Park HS some years ago. Roy remarked that, over the years four students had severely damaged physics laboratory equipment --- and that all four of them have become physics teachers. Interesting! Thanks, Roy.
The following five people could not present lessons today, because we ran out of time. They will be scheduled first at our next SMILE meeting, Tuesday November 1. See you there!
Notes prepared by Ben Stark and Porter Johnson.