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AT OUR LAST MEETING…

  …at Northeastern Illinois University, we were welcomed by Paul Dolan, and what seemed to me like most of the staff and students of the University.  The turnout was great, particularly considering the meeting had been rescheduled due to a snow day the week before. <> 

Paul started the meeting off with some liquid nitrogen demonstrations.  While he was freezing various things (rubber ball, banana, grapes, onion, etc.) he mentioned that the University orders a couple hundred liters of nitrogen at a time and he would be happy to donate some to any teacher who brought their own Dewar.  Dewars cost a little over $100 for a 2 or 4 liter volume.  The nitrogen will last a week inside the Dewar.  A teacher could work up a half hour show and be “Mr. Science” for one day a year.  If you don’t know what to do, come to an ISPP meeting and ask for 5 minutes.  We’ll brainstorm 30 ideas for you.  Fifteen will be doable.  Art Schmidt (Northwestern University) said teachers could also get some nitrogen from him.  As he said, “Many are cold, but few are frozen.”  Take the hint. <> 

Paul passed around various fruits and veggies that he had frozen and smashed.  The grapes were popular. <> 

Announcements… 

…Paul introduced all his students.  We also saw a couple of teachers we haven’t seen for a long time.  There were lots of old friends.  Nate Unterman (Glenbrook North HS) mentioned Physics Day at Great America, Thursday May 10 and Friday May 11.  They are going to have a K’NEX challenge for some prizes.  Check out their website at www.sixflags.com.  He had a flier for the contest and an announcement for another summer Modeling Workshop.  There may possibly be a Modeling Workshop in Chicago.  For information contact jane.jackson@asu.edu.

David Huff (NEIU) made a couple magnetic guns.  The first was a cardboard “V” shaped trough about 70cm long.  He had four cubic neodymium magnets and 9 steel ball bearings that look like 3/8 inch.  (Get them from Educational Innovations at teachersource.com). He glued the magnets 3-ball bearing diameters apart and placed a ball on either side of the magnets.  Then he cocked the device by pulling each ball in the intervals between the magnets back so the orientation from the nuzzle end is ball, ball, magnet, space, ball, ball, magnet, space, etc.  He had a ball in his hand.  He gently rolled his ball into the first magnet and “click, click, click!” – the final ball shot about 3 meters across the room.  Not dangerous but pretty impressive.  You can make a longer one but the cubic magnets tend to shatter. David then showed us an electromagnetic gun he made that shot BBs.  He used parts he had gotten out of the electronic flash of a camera and an old coil.  There are lots of plans for coil guns on the web.  David shot his BB about 8m across the room.  The spark from the camera flash was pretty impressive too.  David said it’s 330 volts.  Be careful.

John Papiewski (NEIU) brought up a can of Dust Off that he got at a local hardware store.  He used it to balance a ping pong ball in the air.  We had the usual discussion of whether or not this is a Bernoulli effect (or a Coanda effect).  John also noted that the longer you ran the can, the colder it got.  There is an inert hydrocarbon in the can (it says) in the liquid state.  It’s expelled as a gas taking heat from the can.  Someone mentioned that the liquid you spray on your car windows to “de-ice” them, takes heat from the window.  The cold window can then ice up on the inside.

Art Schmidt (Northwestern University) brought up a glass bottle of coke and a plastic bottle.  He said it’s hard to see how thick the glass is because the glass refracts the light in such a way as to make the glass look thin.  (He drew a diagram).  He took a large beaker and filled it with water.  When he put the glass coke bottle into the water you could suddenly see the thickness of the glass.  When he tried with the plastic bottle there was no effect because the plastic was so thin.  This is a nice demonstration of light going from one medium to another (other than air).  It was fast and easy. Art also tried the liquid nitrogen in his color changing glass.  He added a little liquid nitrogen to lots of water in the glass as our Chem teachers suggested.  Don’t try it the other way!

Roy Coleman (Morgan Park HS, retired) brought a book called Zap Science with the Klutz logo on it.  It had lots of cute experiments and included the equipment to do them.  Pretty clever.

Roy mentioned our recent snow.  He said he’d always heard that you could tell the temperature by the pitch of the squeak of the snow as you walked over it.  He would love to see some student do a project to see just what the relation is.

He also passed out a sheet “creative answers” to various questions on physics and math tests.  I’m usually not amused by this sort of thing, but this time I really enjoyed some of them.  I made copies of my favorites to pass out to my friends.

Gordon Ramsey (Loyola University) took a 2L bottle and drilled a 1/4 inch hole in the side about 2cm from the bottom of the bottle.  The water would squirt out into a cake pan he brought.  He copied a ruler to produce a paper rule to put in the bottom of the pan and asked: What is the relation between time and the distance the water shot out of the hole into the pan.? We marked every 5 seconds and Gordon called out the distances.  The graph was more or less linear. Gordon passed out a sheet with the relevant equations and derivations.  It also had a few suggestions for running the experiment.

John Milton (DePaul University) brought a book called The Artful Universe Expanded by John D. Barrow.  It’s a melding of art and science.  It brought up the fact that if you cup your hand over your ear you hear a roaring sound.  We had a discussion about whether this sound was an amplification of sounds coming from your body or your outside environment.  We seemed to agree that something was being amplified by the hand forming a sort of Helmholtz resonator.

John also found a Tech Support url (http://www.youtube.com/watch?v=LRBIVRwvUeE) that describes how to make the transition from scrolls to book pages for those of us are trying to transition out of the 15th century.

Paul Dolan (NEIU) had a set of various colors of keychain LED flashlights he got from PhotonLight.com for $16 each.  They include Red (630nm), Orange (605nm), Yellow (592nm), Green (525nm), Turquoise (495nm), Blue (470nm), and Violet (405nm).  You can also get white and IR (880nm).

Paul took a glue stick and pointed the white flashlight in the end.  The other end turned red as the blues were scattered to the side.  He then tried each of the colors and noted the amounts of light that are scattered and transmitted.  The blue and violet lights left the ends of the glue stick almost completely dark.  Those wavelengths given in their information sheet are approximate as these are LEDs and not lasers.  But they’re pretty good.  Paul says they are all available at Educational Innovations.

Lisa Del Muro (Wheeling High School Township Dist 214) passed out a transparency of a cartoon in full color and separated into black, yellow, cyan, and magenta.  You can cut them out and superimpose them on the overhead.  She gave out a sheet explaining how she did it in Windows Photoshop, and some nice activities and questions for the students.  You can also just put them on a white piece of paper in a corner of your lab as a side project.  Thanks Lisa!

Paul Dolan rolled out a bunch of give-aways including one mushy unfrozen broken banana and assorted pieces of equipment.  For our meeting Paul took some refrigerator magnets and remagnetized them so that some had poles on their faces and some had poles on their edges.  They would no longer stick on a refrigerator and Paul asked us what we could use them for.  He measured them at 30 to 50 Gauss.  He gave us a sheet with a description of how he magnetized them and some questions to investigate.

This was a really nice meeting.  Earl Zwicker would say “neat”.  We saw lots of good demos and teaching tips.  Thanks to everybody!

Reported by Pete Insley.

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