Fall Meeting 2004

Northern California/Nevada Section AAPT

Friday & Saturday, November 5-6, 2004

Local Host: Clarence Bakken

Held at: Henry M. Gunn High School
780 Arastradero Rd.
Palo Alto, CA



Friday Workshop

"He's Losing His Momentum!" (11 am - 5 pm) Andria Erzberger, Mike Ugawa & other PTRA's

Approximately 20 teachers spent the day learning about Impulse and Momentum from the PTRA leaders. In addition to two make and take projects, they completed several experiments and worked on examples they could use with their classes.

Friday Evening Social

After a round of light refreshment and drinks, Roger Blandford, director of the new KIPAC (Kavli Institute for Particle Astrophysics and Cosmology) at SLAC and Stanford spoke on the "Runaway Universe". In his talk, he described the Universe as We See It as being Flat, Accelerating and Lightweight. It was an enjoyable evening spent by the group that attended.

Saturday Program

Show & Tell
Scott Perry, Butte College (topic unknown)

Dan Burns, Los Gatos HS, showed a DVD that he has developed with physics examples from the movies.

Julio Barbosa, Hartnell College, demonstrated a student-constructed Electromagnetic Can Crusher. (Misnamed because it actually rips the cans apart into two pieces.)

Steve Hammack, Los Gatos HS, shared a book he found on teaching that he recommends.

Andi Erzberger, retired, talked about the poster set that is going to be available from Science Kit covering everything from elementary particles to the fate of the universe.

Eric Ayers, CSU Chico, demonstrated a vacuum cannon which was able to propel a ping pong ball across the auditorium.

Brian Bella, Hoover HS (Fresno), showed a coupled oscillator using steel strapping and magnets.

Joe Manilo, Watsonville HS, showed a student trebuchet.

Bernard Cleyet, retired, did some microwave demonstrations

Dean Baird, Rio Americano HS, showed an effective polarizer demonstration (you had to be there to get the pun).

Invited Speaker

Luisa Rebull, Spitzer Science Center, Caltech


Dr. Luisa Rebull of the Spitzer Science Center, Caltech will discuss some of the early results from the Spitzer Space Telescope (formerly known as SIRTF), NASA's fourth and final great observatory. Spitzer observes in infrared light, so the Universe it sees looks very different than what we (or Hubble) sees in visible light. Spitzer studies very old and distant galaxies, very young nearby stars, and very dusty things all over the Universe (from nearby comets to distant dusty galaxies).

Invited Presenters

Paul Doherty and Don Rathjen
pauld@exploratorium.edu and donr@exploratorium.edu

Physics Demonstrations from the Expoloratorium

Both Paul and Don are well-known for their creative and clever physics demonstrations as well as their zeal to share them with fellow physics teachers at both AAPT meetings and at the Teacher Institute at the Exploratorium. They shared a number of basic demonstrations done with simple equipment that had good application in the classroom.

Business Meeting/Raffle

Some announcements during the business meeting:

PTSOS - Paul Robinson, Stephanie Finander and Dean Baird discussed PTSOS, a program that NCNAAPT has launched to help beginning physics teachers. To date they have secured funding and held one successful workshop. More are in the works as well as making mentoring connections for the PTSOS teachers.

Future Meetings: Offers were made to host meetings at Menlo School in Menlo Park, the likely place for the Fall 2005 meeting, Foothill College and maybe Chico State.

Elections: People wishing to serve the section as officers need only speak up to get their names on the ballot. Elections will be held at the spring meeting. Some offices that will be open: Vice President for High Schools, Secretary, Program Chair.

Contributed Papers

Modeling the Vacuum Cannon
Eric Ayars, CSU Chico, ayars@mailaps.org

The velocity of a projectile shot from a vacuum cannon is commonly assumed to have an upper limit equal to the speed of sound. A relatively simple theoretical model shows an upper limit that is considerably less than the speed of sound. This theoretical maximum velocity is independent of any parameters of the vacuum cannon, such as diameter and projectile mass. I will discuss the theory, assumptions made in deriving the closed-form solution and problems with the theory which invite further refinement.

What Does a Neutron Star Really Look Like?

Douglas Leadenham, DeVry University, dleadenh@fre.devry.edu

Black holes are by definition invisible, so the next best, visible, general relativity object is a neutron star. First theorized by Tom Gold to explain pulsars, neutron stars and their close relatives, black holes, are hypothetically drawn, interacting with spiraling disks of matter captured from neighboring stars, in magazines and textbooks. None had been captured in a telescope image until 2002, when the unusual object had no other explanation. We will take a look at images on these sites and revise a key size estimate based on general relativity.

Effective Mass of an Unloaded-Hanging Slinky

Phil Gash, CSU Chico, p_gash@hotmail.com

Have you ever tried cacluating the period of an unloaded Slinky? I found both the conventional effective masses for a Slinky (i.e. 1/2 and 1/3) do not work. A discrete model of a Slinky (N coils each connected to each other via a spring) was developed and an expression for the effective mass was obtained. My results show it depends upon the number of coils in the Slinky and is in good agreement with the experimental data.

When You Have to Think Inside the Box

Tim Erickson, Senior Scientist, Epistemological Engineering, tim@eeps.com

We came up with a cool (yet obvious) way to show why the normal force is what it is, and, as often happens when you get an obvious, cool idea, it didn't work - and in a very interesting way. I will show how data analysis comes to the rescue, and leads us to conceptual understandings we never anticipated.

Classical Equations of Motion from Quantum Mechical Operators

Richard B. Kidd, Diablo Valley College, chbks@earthlink.net

It is universally recognized that application of a quantum-mechanical operator to psi-squared, followed by integration, leads to the expectation value of the variable associated with that operator. Less well known is the fact that direct application of a kinetic energy operator to psi leads to a dynamic equation for the KE. However, since the dynamic equations are semiclassical in form, they raise questions of interpretation.

The Physics of the Springy Pendulum

Phil Gash, CSU Chic, p_gash@hotmail.com

At the last regional AAPT meeting Ann Hanks demonstrated a spring-mass system which behaved like both a pendulum and a spring, regardless of the starting initial conditions. This springy pendulum system is modeled as a mass connected to a massless spring which is allowed to swing from its support point. The system Lagrangian is used to obtain the equations of motion which result in two coupled non-linear second order differential equations. One contains a radial and angular velocity coupling term which can be used to explain the back-and-forth pendulum-like to spring-like behavior. The coupled equations are solved numerically and match the observed behavior.

Upcoming Events

o Fall Meeting, SCAAPT, Pomona College, October 26, 2004

o Winter Meeting, National AAPT, Albuquerque, NM, January 8-12, 2005

o Spring Meeting, Joint Meeting NCNAAPT/SCAAPT, CSU Fresno, April, 2004

Posted 11/08/04