The workshop is sponsored by the AAPT as well as the APS Forum on Physics and Society as well as the new APS Topical Group on Energy Research and Applications.
It will be held March 5-6 at UC Berkeley (Evans Hall 10).
The workshop should be of interest to faculty who wish to introduce energy topics into their courses as well as advanced students who might be interested in some aspect of energy research. A similar course organized three years ago was considered a great success. Participants will receive a book of the talks presented.
REGISTER SOON. We sold out when a similar course was offered three years ago.
20 educators attended the afternoon “Introduction to Modeling” workshop lead by Lee Trampleasure and Jon Rockman. Educators were lead through the development of one of the Modeling “paradigm labs.” The lab used constant velocity cars to develop position vs time data that could be graphed to determine the average velocity of the cars. After groups graphed their data, they created whiteboard presentations of their results. After a discussion of the results, Lee presented data from his classes this year, showing the results of 20 student groups.
For more information on Modeling Instruction, visit modeling.asu.edu.
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:
At every section meeting one of our most popular portions is the Share n Tell during which participants have five minutes to share a demo, idea, concept, book, problem, example, etc. Talkative participants must fear the dreaded gong at the end of five minutes. Below please find notes and relevant links from the special double session of Share n Tell from our Fall NCNAAPT Section Meeting and mini-conference:
Don models Piezo Electric Cars
Don Payne, Carondelet High School
A Piezo Electric popper (spark fed) has been adapted to drive a small toy car. A film canister is filled with either ethanol or Bonaca breath spray. By igniting the propellent the can be shot in one direction as the car moves in the other. Can be used for momentum collisions or projectile motion and potentially adapted for use with photogates. Black film cans with gray lids with a lid work the best and a Nerf ball was added tot the launching end of the can for safety for projectiles. Nicknamed as the “Bonaca Cannon” at the conference, the car is made from a small wood base, Pisco (?) aluminum axle wheels and electric leads for ignition.
Piezo Electric Car
Piezo Electric Car
Piezo Electric CarPiezo Electric Car 4
Paul Robinson, San Mateo High School
Horace (Rog) Lucidio taught in Pittsburgh and then Fresno. He has since retired and published a book called “Educational Genocide” just recently out. It is available from Amazon or AbeBooks, and comes highly recommended. Read the press release here.
Bernard C, retired
Bernard demonstrated a “Poisson’s Spot” demonstration, misnamed because you shouldn’t get light behind a barrier which in this case is a 4” “ball bearing” used to block the microwave signal AC Amplifier (with sound signal so it doesn’t need to be in the dark). Can be shown to block specific zones so that it acts as a positive lens and increase the size of the signal using Fresnel Zoning.
Bree models Center of Mass projects
Bree Barnett Dreyfuss, Amador Valley High School
Bree shared a “Center of Mass” Project that students do while studying Torque and Center of Mass. The project is adjusted for a variety of levels including freshmen in Conceptual Physics. There is a website with details and YouTube video that explains the details of the project to students. Sophomores to Seniors in regular Physics have to bring in a balanced object, either a mobile, 3D sculpture or flat oddly shaped object. The flat character/ geographic region is the most popular and allows for the most creativity. Students have also used powerpoint, made videos with classmates and even hand drawn animations in order to demonstrate their understanding of Center of Mass. For younger freshmen, the project is restricted to create a flat creative object and bring it in to class. Then together, they learn how to find the center of mass of their object using a plumb bob.
Cailin models her homemade wind tunnel
Cailin Creighton, iFly educational leader
Cailin is in charge of the education program at the Union City iFly facility and has offered affordable field trips for teachers. She shared models and instructions of a handmade vertical wind tunnel out of a cereal box and plastic bottle. Instructions to come soon. Cailinused a Kellog’s 18 oz cereal box and an Archer Farms water bottle – plastic not glass to create the frame of the wind tunnel. A 80 mm commuter fan hooked up to a 9V battery runs the fan and allows a light object like tissue paper to fly. This model models the Hollywood (single side tunnel) while the local Union City one has two sides of fans feeding in to the tunnel. Turning vanes are not necessary for the cereal box model due to the simplicity of the design. It was suggested to try adding dry ice to simulate a tornado. 1” Styrofoam balls cut in half will fly, while a whole ball will not fly which is interesting because they have the same surface area but a different weight. Cailin’s contact information is Cailin@iflysfbay.com.
Paul and Paul model reaction time
Paul Doherty, Exploratorium
A baseball bat is adapted to be used for a reaction time test.
Paul shared the classic Reaction Time experiment adapted to work for a baseball bat that is marked with reaction times. Average human reaction is 0.16 s, volunteer Pablo got 0.22s, then 0.2 s which is consistent with experiments as students improve with time.
Putting a stiff card at the top of the baseball bat acts as an amplifier. You can strike the bat at different locations and hear an amplified thud. The sound will decrease as you reach the “sweet spot” which is a vibrational node. This is why hitting a home run on the sweet spot feels better than hitting off the spot.
Don Rathjen, Exploratorium
A Fan cart is helpful in teaching Newton’s Third Law by moving the fan and sail positions to show that when both are on the same cart it will not move. Don has a fabulous design that is very low friction. Don also added a waterbottle that was cut in half with the “sport top” that pops up that can be used to create a consistent drip timer. This can be added to the fan cart to work as a drip timer for motion to model motion.
Don Rathjen's Fan CartNewton, NC's 3 laws
Lee Trampleasure, Carondelet High School
Lee (who had lost his voice) shared a humorous PowerPoint on Newtons three laws (Newton, North Carolina, that is) with single picture explanations of each of Newton’s Three Laws:
1st law: 35 mph Speed Limit sign
2nd Law: “no left turn” sign
3rd Law: “no parking” sign
Pauline models torque
Pauline Seales
Pauline described a demo in which she asks a “strong” student to bend a nail with their bare hands, which they can’t do. She then asks a “small” student to bend it and hands them two pieces of metal pipe that are inserted on each end of the nail (increasing the lever arm distance) and they are able to bend it easily.
Pauline also modeled using a pre-cut mop handle attached with a PVC pipe to show how balanced Torques does not mean balanced forces. Students often don’t believe her and have to weigh the broom head (heavier) and handle (lighter) themselves because they don’t believe her.
Pauline with precut mop
Dean Baird, Rio Americano High School
Showed Simple Harmonica Motion:
Simple Harmonica Motion
Dean also discussed a large mural of white light reflected on an equilateral triangle outside his room with almost the right angles. He showed a video of a Newton’s Cradle that does not behave normally as discussed in his blogpost.
Paul Doherty added that the Exploratorium recently created a large Newton’s “ridable” Cradle with 1 meter diameter Lexican balls. Paul also told us about the Exploratorium’s After Dark adult only program that goes from 6-9pm, on the first Thursday of every month.
Rob Benn, American High School
Using video in the classroom using iMovie, iPods, iTouches, etc. in order to model Bridges, motion at Great America, etc. Can also be used with high speed cameras. VideoPoint is additional software that you can use. The FH100 Casio will do 1000 frames/ second but is $300. Students participate in Knieval Physics which makes for interesting videos. Due to the wealth of information available from Rob, he was encourage to do a workshop next time.
Dean Baird, Rio Americano High School
Dean showed an additional short film of a Newton’s Cradle in which the balls appear to fly apart. After showing a hint video we were able to see the answer, all videos available on his blogpost.
Dobbson models a Gaussian Cannon
J Robert Dobbson
Dobbson shared a Gaussian Cannon that can be made rather than bought with ½” steel ball bearings and neodymium magnets on a plastic ruler. Having an assistant pull the last ball, last two balls and last three balls off the end you can learn that the approximate magnetic strength changes with proximity to the neodymium magnet. Allowing the first ball to fall down a small incline the loss of potential energy becomes kinetic energy. The ball also gains energy as it is attracted to the magnet and as the energy grows the last ball flies off at a larger velocity.
Dobbson also shared a coil of magnetic wired that he had to modify so that it appropriately showed the magnetic field inside the coil without being affected by the lights. He coiled 10 cm, made a Uturn in the coil for 20 cm, used another Uturn and then another 10 cm.
Rodger talks about temperature
Rodger Moorehouse, Pomona
Rodger discussed the history of different temperature scales and their origins.
Bree Barnett Dreyfuss, Amador Valley High School
Bree shared a variation of the Blinky Light activity from her website as well as an online game about Torque called Levers.
Paul Robinson, San Mateo High School
Paulshared the ramp he designed which is very repeatable and consistent. He was unable to show his baseball videos but they are available on his website.
