Paul gave us a brief history of the Exploratorium and its growth over the years. Participants were then split into two groups to explore the Exploratorium’s favorite exhibits. Don and Paul gave tours of the museum and met back together for one big demonstration. Highlights include exploring the reflective properties of the dome at the Palace of Fine Arts and the hidden resonance tube inside one of its pillars. Paul demonstrated the “whirly” sound resonance tube in a larger-than-normal format. A video will be available once its edited.
Adam uses movie clips to teach traditional problems to engage students in the problem. (book available for signing) Some movies are good to show to explore “good science” and data can be collected from the clips in order to create problems. Others are examples of “bad science” and can be used to generate discussions about what is wrong based on the science students know. Adam likes action movies such as Spiderman, Spiderman 2, Spiderman 3, XXX, 2001: Space Odyssey, etc.
Dave Kagan introduced the rules & procedure for Share ‘n Tell including the dreaded gong!
Participants at the Spring 2011 NCNAAPT Conference
Bree Barnett Dreyfuss – Amador Valley High School
Recently Bree used Energizer AA batteries in a physics lab only to find that several students were being shocked by them. It turns out that the plastic covering on the bottom terminal of the battery was not very well covered and the multi-stranded wire used in the experiment was poking underneath the covering and shorting out the battery. Duracell AA batteries have a better covered bottom terminal. Energizers can be fixed by putting a hole reinforce on the bottom terminal so that the gap is sealed. If you attend her workshop later in the day you can try shocking yourself as her students did.
Tom Rossing – Standford University
Tom demonstrated a noise maker to discuss resonance in open and closed air tubes, self-resonant tuning fork/choir chime made from extruded aluminum.
Jeff Jorgensen – Arroyo High School
Introduced his Case study Portfolio – a how-to about his “case study” activity. Case studies on a variety of topics are available on his website. You can also access his site by going to http://ahs.schoolloop.com and under “Directory,” then “Staff,” choose Jeff to access his webpage. Feel free to email him as well: jjorgensen@slzusd.org.
Don Rathjen – retired from the Exploratorium Teacher Institute & Foothill High School
Don demonstrated a simple ballistic pendulum (used to measure muzzle velocity) made Teacher Institute-style with a plastic bottle and string. It allows you to measure the muzzle velocity of a toy dart gun. Don’s activity write-up is available here.
Frank Cascarano – Foothill College
Frank shared an angular momentum demo using cordless drill, pvc pipe, drill bit, rotating table. When standing on a rotating platform the drill is run like a helicopter, that makes him rotate in the other direction to conserve angular momentum. Frank’s website is here and his email is FCPhysics@gmail.com.
Dean Baird – Rio Americano High School
You know the Power Balance bracelet? He analyzes the videos and shows that the bracelet does not in fact make you stronger, his YouTube lesson shows the fallacy. He first delved into the phenomenon in his blog entry “Power Balance Bracelet,” and is now working on a full lesson on it.
Dean also demonstrated a jelly baby wave machine using Dots candy rather than buying the expensive demo. Put two dots per side on a bamboo skewer and attach with duct tape. Dean discusses his wave machine in “Connecting the Dots” on his blog, “The Blog of Phyz.”
Clarence Blakken – Gunn High School (retired) and Vernier
Vernier is giving out awards; Clarence wanted to share the new probes from Vernier and his Weblabs available on his website. Also, Great America Physics Days are coming soon! Be sure to check out the Electronic Data Collecting center at the Great America Physics Day.
Tucker Hiatt – Branson/ Wonderfest/ Standford University
Tucker discussed grading strategies including using an error range as we do use in science. For example if they got a 35/45 +/- 3 points may help deal with complaints.
Dan Burns – Las Gatos High School
“A Discovery is an event that reveals your ignorance.” – Dan Burns
A light shown in an LED creates a voltage. A red LED shown into a green LED will not produce a voltage to get it to light. Red LEDs do not have enough energy to give to a green LED (that has a larger band width) but a blue LED can “power” a green LED. A UV LED does not light any color, despite the fact that they have a larger amount of energy. Resource: Center for Nanoscale System Institute for Physics Teachers, reference the “Phantasic Photon” lab for more details.
Veenu Shekhar – Silicon Valley Labs
Veenu helped to manufacture labs about LEDs & solar cells for high school students. Have a grant from the EPA and working on more to produce labs for electronic labs for middle and high school students.
Jeff Arrigotti – PASCO (thank PASCO for the donuts!)
Jeff will be giving away a car track for dynamics and collisions (full set up with springs, etc. and a second one with Physics kit). The car tracks can be attached to several different set ups for multiple experiments.
Gunjan Raizada Chakravarty “Dr. G” – “Sowing the Seed of Physics”
Dr. G has been doing Physics workshops for elementary kids in libraries – gave an example of an inquiry style activity that she does with children. More information is available on her website.
Bernard Cleyet – retired
Explored the conductivity of the hot glue to see if it was the cause of a faulty glue gun (as reported on a PTSOS listserve). Also ask people to respond to a quick questionnaire.
Paul Robinson – San Mateo High School
Lunch is not provided – we will be providing refund for funds collected.
National level (AAPT) update – national meetings need more attendees and possibly reduce number of meetings?
Mentioned his website, www.laserpablo.com and his lab manual is out of print – available online now
By Don Rathjen and Paul Doherty (absent presenter Sebastian Martin) from the Exploratorium
A link to the powerpoint that accompanied this presentation will be linked soon.
“Blinky Lights” is a nickname for a small LED light by Inova called a MicroLight. The light has three settings: bright, dim and blinking. Pressing the light once sets it to bright which is on constantly; two clicks is dim and then three clicks is blinking. The dim setting is actually oscillating on a duty cycle that blinks it back and forth very fast. You can see this by setting it to dim and then waving the light in front of you. The “slow blink” is actually a 3Hz blink rate.
Using a Radio Shaq amplified speaker (~$15), Paul hooked it up to a solar cell and could audibly hear the change in the sound. He analyzed the sound using a free audio analysis software called Audacity and found that the light had 100 cycles/ second. The frequency was actually 97 Hz +/- 3%. Solar cells are attached to a mono mini 1/8” phone jack can be plugged into the speaker or an oscilloscope. The duty cycle is about 10% so that it blinks once every 1/100 hundredth’s of a second, a frequency of 100 Hz. It has recently been discovered that some new ones may be at 200 Hz on dim.
The human eye refreshes in such a way that one bright flash at least one microsecond long will cause the cones to fire for one tenth of a second. The amount of time that the cones continue to flash after depends on the brightness of the light. The memory of a retina is 1/10 of a second but the eye “forgets” 1/8 of a second later.
Blinky Lights can be used to determine the speed of motion of an object if the distance is known. You count dots (100 dots = 1 second). Cameras used have to have a longer exposure time (preferably on a tripod) in order to catch prolonged motion. Cameras can also be on “night setting” on cheaper cameras or even camera phones with the flash off. Either way the exposure time has to be increased; some actions will need only one second while some more artsy photos will need longer. A simple picture like the bike wheel below has a one second exposure time:
Paul demonstrates circular motionBlinky Lights attached to a baseball bat
Paul demonstrated that the Blinky Lights can be attached to a baseball bat in three places: at the handle, near the head and at the sweet spot. When hung loosely from the handle and struck at the bottom, the baseball bat travels but the blinky light at the sweet spot reveals that the center of mass will travel in a parabolic shape. If struck at the center of mass it will translate to the side with rotation in the other direction. You can find the center of percussion by finding the place that allows the bat to fall straight down without rotation.
Blinky Lights can be attached to a long PVC pipe as well to explore vibration images, resonances, etc. Qualitative observations can be made about several objects without measurements. Blinky Lights can be helpful to show time lapse of specific types of motion.
Blinky Lights are very helpful to show freefall and the acceleration due to gravity by attaching a blinky light to a ball. Two blinky lights on opposite sides can be used to experiment with different pitches.
Blinky lights show Free Fall
Don explored how to update role of the old fashioned spark timer using blinky lights. Without measuring time precisely you can say the distance between each pair of dots is a “tic” and use it as a unit of time. By measuring the distance in between you can determine the distance per “tic.” Don showed how by cutting it up you can create a velocity to time graph with each unit of “tic.” This can be adapted with a blinky light on the same moving object. By counting blinks and using a measuring device such as a meter stick within the shot you can create the same type of graph.
Fan Cart GraphDon used multiple cars to model different types of motion.
Don also modeled how to show acceleration of a two speed shifting toy car as it shifts speed. Blinky Lights can be attached to a variety of cars in order to model different times of motion including constant velocity, acceleration, going over a hill, a “loop-de-loop,” etc.
A 2 Speed Shifter Car modeled with blinkies
Paul and Don also shared information about the Teacher Institute at the Exploratorium and several of their electronic sources listed below:
