# Fall 2012 Conference Share ‘n Tell

Tom Woosnam, Crystal Springs

Tom showed us a conducting experiment (picture to come) with two cans and a two copper wires that do not touch and attach to a coup of water. After the cup of water is filled a small neon bulb that that is connected to one of the two copper wires can discharge repeatedly. Tom’s best guess as to why it flashes is that one of the metal cans becomes randomly charged, say negatively, and that negative charge travels up the conducting materials to the water and repels electrons through the other wire to the other side that builds up potential.

Dan Burns, Los Gatos High School

All materials available at http://prettygoodphysics.wikispaces.com/PGP+Circular+Motion

Dan modeled of the amusement park ride “The Rotor” in which participants are suspended in the air during rotation. Dan has modeled the ride in his classroom using a lazy susan and a cylinder of thick paper. A small stuffed toy can “stick” to the side of the cylinder if spun fast enough. He can calculated the angular velocity using a small tab sticking out of the cylinder and a photogate.

Dan Rathjen, Exploratorium

Dan has created a toothed wheel that can attach to a drinking bird heat engine that can be used to show the transfer to mechanical energy. Students can determine the equivalent of “1 duck power” worth of energy and determine how that relates to horse power (1 billion duck power = 1 horse power). This material and more are available on Don’s website.

Mark Hurwitz, Lick-Wilmerding High School

Mark demonstrated his “Screw Electromagnetism” activity. Students are given a small neodymium magnet to attach to the head of a screw and hang it from the positive terminal of a C battery. A conducting wire attached to the top of the battery (negative terminal) to the neodymium magnet and you will see it spin! This is an example of a homopolar motor.

Frank Cascarano, Foothill College

Frank has several video solutions on his website with link with problems and solutions that have been worked out and recorded for students. Frank has used a tablet with a screen capturing software to complete these video. Frank said he had heard about screen capturing and tablets years ago at a NCNAAPT conference and it took a few years to get the materials but he has really enjoyed it.

Scott Lubbs, Evergreen Valley High School

Plastic water bottles used to model thermodynamics cycles. An empty water bottle that is capped is squeezed (work added) and the temperature is increased as it is squished. Then he lets the water bottle return to room temperature and when the water bottle is stretched back out it becomes colder. Be aware of students that want to pop the top off!

Bill Papke – American River College, retired

Bill recalls the beginning of the NCNAAPT organization and the shift in membership from predominately college and universe oriented to mostly high school. Bill recognizes Paul Robinson for his contribution to the support of high school teachers. He also mentioned the Analog magazine that discussed Science Fiction as well as the scientific facts that supports it. The two sections he spoke about are available if you email Bree at Secretary@NCNAAPT.org.

Xavier Maruyama – NPS, retired

“Just because its metric don’t mean you’ll get the right answer!” OR ”You get what you pay for in the bargain table!”

Xavier bought a bargain tape measurer that measured 5.5 m = 18 ft that was providing wrong results for basic length measurements. A Chaku is about a foot long but it is a Chinese and Japanese standard measurement for construction. Unfortunately, the Chinese and Japanese Chaku lengths do not match.

Bree Barnett Dreyfuss, Amador Valley High School

Bree demonstrated a LiveScribe pen which produces Pencasts (talking pdfs) that she uses with students. An example that Bree uses is available here, although you must download it for it to work. Livescribe pens also have many applications for students that have difficulties taking notes during traditional lectures and in meetings.

Dominic Calabrese, Sierra College

Dominic demonstrated a Whimhurst machine attached to a dissectable Leyden Jars that was charged off the machine.  He then carefully discharges the Leyden Jar using a wood stick and disassembles it. When he reassembles it it can still be discharged because the charge is stored in the insulating material, not the conductive material. Of course this demonstration is done the best when theatrics are used.

Aviva Shackell, Sierra College

Aviva used a document cam to document Chladni Plates as a demonstration of 3D standing waves in a metal plate. The patterns abruptly change as resonant frequencies are found during a frequency sweep.  Many videos are available online if you don’t have a set for yourself.

Ann Hanks, PASCO

Ann demonstrates the rotational inertia sticks that are identical in weight but have that weight distributed differently. One (red) has the weight concentrated in the middle and the other (blue) has the weight on the outside which is more difficult to spin. Students can hold each stick at the end and feel the linear inertia is similar but the rotational inertia is quite different.

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