Saturday, December 22, 2018
"Challenge Accepted" is the title of their report; IIHS increases the rigors required for vehicles to earn the top ratings. They keep the goalposts moving to compel manufacturers to better protect occupants each year. IIHS hopes that the 57 models that qualified for this initial list will be joined by more models as 2019 moves forward.
Years ago, Griff Jones worked with the IIHS to create the classic, Understanding Car Crashes: It's Basic Physics. It's an excellent capstone for instruction in mechanics. As mentioned in a previous post, I developed a fairly robust single-period lesson around vehicle safety and Jones' video.
YouTube Physics—Understanding Car Crashes: It's Basic Physics @ TPT
It brings the physics home to the students and gets them talking about vehicles they ride in or might aspire to own. I hope the lesson plants a seed that will get them to make vehicle safety and crashworthiness a primary factor when they consider a vehicle purchase.
As a native of Michigan, I was disappointed to see only one American model listed as a Top Safety Pick. Japanese, South Korean, and German makes and models proliferate these lists. I hope US nameplates step up their game, but their track record does not nourish my hope.
Package Thief vs. Glitter Bomb Trap
Students might—at times—question the value of learning about centripetal force and such. You just never know when you might use it to your advantage.
Here's Sean Hodgins' less viral video detailing the build.
Building the Glitter Bomb with Mark Rober
The notion of delivering a modicum of justice to porch pirates strikes a chord in most of us. I'm confident that simpler solutions cannot be far away. With luck, this project will soon be an amusing tale of "back in the olden days".
Some viewers were skeptical of some of the reactions. Rober confessed to being too aggressive in seeking glitter bomb reaction footage and pulled a few of the clips after determining they were not genuine. I saw one YouTube "skeptic" who seemed a few marbles short of a full deck ranting that the whole enterprise was paid for by Amazon. This guy seemed to be hoping that making a vile video would generate viral video revenue. And no, I'm not going to link to it here.
Of course, one takes some risk slapping back at porch pirates. They cast themselves as sociopaths by their criminal conduct to begin with. And having their poor judgment highlighted to them may not set them on the right path.
Still though, a nice story of using STEM skills to deal with a common, real-world problem. STEM coursework isn't the easiest, but mastery of some of it can make you powerful, indeed.
[Here at The Blog of Phyz, our favorite viral video is still Dan Burns' Gravity Visualized.]
Tuesday, December 04, 2018
All lab groups: cardboard toilet paper roll, PVC pipe, wood dowel of similar radius and lengths; 0.5 kg brass cylindrical mass, hollow plastic ball, ping pong ball, golf ball.
Shared among groups: wood dowels cut the same length and of the same radius as the brass mass, empty oatmeal container, empty paint can, wooden sphere, "sloshy" cans of broth and "nonsloshy" cans of chili.
Students were confused at first at the sheer amount of materials so I made a list on the board for them of everything and added "hollow" or "solid" after each.
"Do we have to write down hollow or solid?" they would ask. I told them they might want to make note of it. Those that didn't ended up adding it later when they realized that information helped them to see patterns in which object "won" the race.
Students were to race two objects at a time down a stack of two whiteboards, releasing them at the same time using a meter stick. Often their predictions were wrong, they usually conducted repeat trials to be sure of their results. There were lots of side experiments going on, racing objects against each other I had not required. (Part of my ulterior motive for having so many objects available to them.)
Their exclamations of frustration or elation would have confused anyone walking by:
"What is with this sloshy can? It always wins!"
"No!!! Tube you were supposed to beat the ping pong ball!"
"Wait .... why the heck did the golfball win?"
"Why did they tie!?"
"No no no do it again, you started the oatmeal before the chili."
I was laughing all day and it was great to see them conducting their own experiments to try and figure out why one won out over another. One student vehemently insists it was voodoo magic.
In one class two groups merged to try and release more materials at once:
Which of course lead to what I wanted to test as well: All the things. At once.
So I grabbed a wooden box I had in the prep room that was wide enough and we set about it. Two students released them all but we found using two different meter sticks made the release different for the two sides. We used an equivalently long piece of PVC and got the following results:
I took a still from the front video and we ranked the objects as best we could. A grid on this surface could help make it definitive.
Students had recorded the mass and radius of each object the day they completed the lab. The next day, after learning rotational inertia formulas, they were able to calculated an inertia value for each object. We did not take the different amounts of friction on each object into account but they saw the general trend that the objects with equations that would have higher inertia values if they had the same mass and radius into account were last to the race. The solid objects beat the hollow ones every time; solid objects were #2-5 and hollow cylinders were #9-12. Sloshy vs nonsloshy is a bit more complicated and students don't calculate a rotational inertia value for them. After some information on rotational kinetic energy they realize that the higher rotational inertia an object has, the more energy is going into its rotation and less is going into its translation therefore it will "lose" the race. Applying this idea to the sloshy can students realized that the sloshy contents aren't rotating (much) and therefore that was a lot of mass that was just translating down the ramp. The nonsloshy can however, has a lot of mass to rotate in that can and acts more like a solid cylinder with a lot of rotational energy and less translational kinetic energy than the sloshy can.
The kids really enjoyed the lab and while it was not as accurate as it could be it really helped them to understand what affected an object's rotational inertia and I think set us up really well for rolling next week. Almost the entire lab fits into three oatmeal containers for storage as well.
Friday, November 16, 2018
Let this be our last post about the kilogram. We've had posts on the kilogram
It seems we have at last moved away from the physical kilogram standard, Le Grand K, near Paris (and it's many replicas around the world). The new kilogram is based on electric current, which seems counter-intuitive at first.
The new definition of the kilogram will change the way we weigh everything
But wait: there's more. The mainstream media's stories omitted changes to the mole, kelvin, and ampere.
Veritasium has the story.
Friday, November 02, 2018
Stars, exoplanets, galaxies, and such. This is the grooviest stuff in Earth Science if you ask me.
The Hubble retrospective, Nova's Invisible Universe Revealed, puts a catch in my throat and tears on my cheek every time I watch it.
And when you get Alex Filippenko and Neil deGrasse Tyson in the same video (as you do in The Universe's Life and Death of a Star), I'm in!
The hot links to the videos below were active when I posted this, but may well have moved on by the time you read this. Your resilience and resourcefulness will get you access to these documentaries.
Earth Science Series 5: Astronomy Beyond the Solar System
5.1. Stars. The Universe: Life and Death of a Star
The History Channel wants you to go through them to gain access.
5.2. Exoplanets. NOVA: Life Beyond Earth 2. Moons and Beyond
5.3. Hubble Space Telescope. NOVA: Invisible Universe Revealed
5.4. Galaxies The Universe: Alien Galaxies
Here's a link to the Lessons of Phyz question sets at Teachers Pay Teachers:
Earth Science Series 5: Astronomy Beyond the Solar System
Thursday, November 01, 2018
He and I (and other similarly interested Michigan friends) enjoyed Jim Loudon's Astrofests religiously back in the day. And that 401 class was a shared experience, to be sure. Humbling, but at least it was taught by the outstanding Dr. Jean Krisch, who pointed me in the direction of the inimitable Walt Scheider when it came time for me to do my student teaching. I was flooded with fond memories when science rockstar, Dan Durda, popped up on the screen.
But I digress. It's a blog; digressions are allowed (if not openly encouraged).
As always, the hot links to videos shown below will likely expire and move on. Use your judgment, resources, and Google-fu to access the content. These videos do tend to be available for purchase.
4.2. The Solar System. NOVA: Life Beyond Earth 1. Are We Alone?
4.3. Stars. NOVA: Secrets of the Sun
Wednesday, October 31, 2018
After yesterday's behemoth, this series turned out to be on the brief side, weighing in at a mere 7 pages of content (7 student pages; 7 key pages). But it's core Earth Science...
Earth Science Series 3: Tectonics, Volcanoes, and Earthquakes
3.1. Plate Tectonics. Naked Science: Colliding Continents
3.2. Volcanoes. NOVA: Deadliest Volcanoes
I streamed this one from the PBS app on my AppleTV.
3.3. Earthquakes. NOVA: Deadliest Earthquakes
I streamed this one from the PBS app on my AppleTV.
Here's the link to the Lessons of Phyz question sets at Teachers Pay Teachers.
Earth Science Series 3: Tectonics, Volcanoes, and Earthquakes
Tuesday, October 30, 2018
The hot linked videos (where available) below may or may not be the best versions that currently stream. Video hot-links are highly ephemeral. Use your Google-fu or purchase hard media versions for better results.
Series 2: The Atmosphere, Weather, and Climate.
2.1. The Atmosphere. National Geographic: Our Atmosphere
2.2. Weather. Modern Marvels: Predicting Weather
2.3. Storms. NOVA: Megastorm Aftermath
2.4. Climate. National Geographic: Before the Flood
This one streamed for free for a short period after it was released. It now streams for a fee. In fairness, it is a major production that is very much worth owning.
Here's the Lessons of Phyz link to the question sets on Teachers Pay Teachers:
Series 2: The Atmosphere, Weather, and Climate.
Monday, October 29, 2018
But as mentioned in other posts, I can never bring myself to show a video presentation cold. There needs to be a support document to help keep students focused on the content. The resulting video question sheets have been added to The Lessons of Phyz at Teachers Pay Teachers.
For this post, I'll try to hot link to the videos that go with each question set. Hot links often go cold as time goes by. If a video streams, one's Google-fu doesn't necessarily need to be strong to locate it.
Earth Science Series 1: Science, Mapping, and Water
1.1 About Science. NOVA's The Secrets of the Psychics
1.2 Mapping. NOVA's Lost at Sea: The Search for Longitude
1.3 Water: How Earth Changed History: Water
1.4 Water: National Geographic: Earth Under Water
The question sets on TPT can be found at this link:
Earth Science Series 1: Science, Mapping, and Water
Friday, October 12, 2018
"Will we ever have to deal with turns on an incline?"
Oh yes kids, but lets build up slowly.
I created this worksheet that referred back to sample and back-of-chapter problems in the textbook. Students worked on increasingly difficult problems with a partner before we reviewed. Here are a key for the worksheet and a key for the textbook problems.
To introduce the concept I delved into the cabinets left to me by my predecessor and found the toys I needed. I raised the whole demo on a wood stand to raise it up. I found a double lane flat track (in yellow) and a banked Hot Wheels track (in orange). Amazingly the Hot Wheels track fit into the inner lane of the flat track. For my first period I used clay and ring stands to hold up straight track to feed cars into each lane. By the next period I added a third straight track to feed one car straight to the wood support, with no turn. By the last period I added color coded signs ...
When I demonstrated this for students I ask students what will happen to the car that goes on the "no turn" track. They correctly guess that it will continue straight so I ask why it doesn't turn. It may take a second but they realized, "There was no force to push it into a circle!"
So then we drop the second car down the "flat turn" track and the initial ramp is high enough that the car rides the edge of the track through the whole turn. I ask students which force kept the car going in a circle and they realize that it isn't the force of friction but the force from the wall in this case. We talked about how that wouldn't be good for "real cars" and that instead we prefer a force of friction to keep our cars going around a turn.
The final car goes down the banked turn and while it may briefly touch the wall it doesn't ride the wall like the flat turn. They notice the banked orange track is about as smooth as the flat yellow track so I wasn't sneaky and just adding friction. Then I asked them what force caused the car to go around a circle and they realize its a portion of the normal force.
Here is a video of the three cars being sent down the ramps at the same time:
The radius and coefficient of friction for the two turns are not the same and I did not bother to match the masses of the Hot Wheels cars I grabbed. I did not introduce any quantities for students other than identifying which force was causing the motion. It helped for my students to see the differences in the types of turns and they loved being able to run the cars down the tracks themselves. For a quick set-up it did well to help show my students the differences for each type of turn they were going to work through.
Wednesday, September 12, 2018
Holton's talk was clearly not sanctioned by the good people of The College Board. But his expression of frustration and exasperation with AP1 resonated with me. Apparently my expression of frustration and exasperation resonated with him, too. (He cited my lament in his talk.) His critique was much more robust than mine was.
A small group of us had a combination perambulation, ventilation, brainstorm as we migrated to our next sessions.
We concurred that dropping AP Physics 1/2 from a school's curriculum constituted a marketing challenge for any school that would dare to try. We now advertise and market our schools on the basis of the breadth an scope of Advanced Placement offerings and performance.
AP courses are to be added to a school's course catalog; not removed. That other high school being visited by shopping 8th-graders and their parents is offering AP Physics, so your school must match.
One idea we tossed around was running a course that would prepare students for the SAT II Physics exam. Does anyone, anywhere run such a course? I'd love to hear from anyone teaching such a course. For now, it's just a thought. And The College Board still wins.
I know AP Physics C fans are happy with their exams. Abandoning AP1 and AP2 for an SAT II-based course is a different set of conversation. One might argue that outstanding performance on the SAT II Physics wouldn't get students out of any physics course at a college or university. I would hasten to add that outstanding performance on an AP Physics 1 or 2 exam doesn't necessarily exempt a student from intro physics courses at college, either.
Here's what the SAT II Physics exam covers. (A physics content-based assessment: how tantalizing!)
Kinematics, such as velocity, acceleration, motion in one dimension, and motion of projectiles
Dynamics, such as force, Newton’s laws, statics, and friction
Energy and momentum, such as potential and kinetic energy, work, power, impulse, and conservation laws
Circular motion, such as uniform circular motion and centripetal force
Simple harmonic motion, such as mass on a spring and the pendulum
Gravity, such as the law of gravitation, orbits, and Kepler’s laws
Electricity and magnetism 18%–24%
Electric fields, forces, and potentials, such as Coulomb’s law, induced charge, field and potential of groups of point charges, and charged particles in electric fields
Capacitance, such as parallel-plate capacitors and time-varying behavior in charging/ discharging
Circuit elements and DC circuits, such as resistors, light bulbs, series and parallel networks, Ohm’s law, and Joule’s law
Magnetism, such as permanent magnets, fields caused by currents, particles in magnetic fields, Faraday’s law, and Lenz’s law
Waves and optics 15%–19%
General wave properties, such as wave speed, frequency, wavelength, superposition, standing wave diffraction, and Doppler effect
Reflection and refraction, such as Snell’s law and changes in wavelength and speed
Ray optics, such as image formation using pinholes, mirrors, and lenses
Physical optics, such as single-slit diffraction, double-slit interference, polarization, and color
Heat and thermodynamics 6%–11%
Thermal properties, such as temperature, heat transfer, specific and latent heats, and thermal expansions
Laws of thermodynamics, such as first and second laws, internal energy, entropy, and heat engine efficiency
Modern physics 6%–11%
Nuclear and particle physics, such as radioactivity, nuclear reactions, and fundamental particles
Relativity, such as time dilation, length contraction, and mass-energy equivalence
General, such as history of physics and general questions that overlap several major topics
Analytical skills, such as graphical analysis, measurement, and math skills
Contemporary physics, such as astrophysics, superconductivity, and chaos theory
Friday, September 07, 2018
|With IR Cut Filter Without IR Cut Filter|
|Remote Control Using iPhone Selfie Camera|
|IR Cut Filter on a Webcam Lens|
Once the IR cut filter is removed, replace it with a filter that only passes IR radiation. I use a Wratten #87C filter. Edmund Optics sells one for $175. That is expensive but it would be enough to make many near IR cameras. The filter is large enough to be attached over the lens of the camera. This allows pictures to be taken with and without it for comparison. I chose to place it inside the lens housing of the webcam so it is more secure. I can then use an unmodified webcam for comparison pictures. You can find less expensive Wratten 87C filters on eBay for $30-$40.
|Unexposed, Developed Color Film|
|View of My Classroom Through the Material from a 3.5" Floppy Disk|
|Continuous Spectrum Compared to Spectrum After Pass Through IR Cut, Floppy, Color Negative, and Wratten 87C Filters|
A near IR webcam is very useful in the classroom but awkward for taking around town and country. Many people would have difficulty successfully taking apart a webcam AND putting it back together in working condition. I know I did. Another option that overcomes these obstacles is the Sony Nightshot line of cameras. They have a switch that slides the IR cut filter out of the optical path. They also have IR LEDs to illuminate objects so they can be seen in total darkness. I use a Sony MiniDV Handycam DCRHC40 that I purchased new in 2004. There are usually many inexpensive Sony Nightshot cameras for sale on eBay. To convert a Nightshot camera to a near IR camera all you need to do is place an IR pass filter over the lens. Either a Wratten 87C or one made from developed, unexposed color film works well. I made a card stock holder so I can quickly attach and remove the filter to take near IR/visible comparison pictures. I also cover the IR LEDs with electrical tape although they are useful for some applications.
|My Sony Nightshot Camera With IR Pass Filter Installed and Tape Blocking IR LEDs|
|Fabric in Visible Light Same Fabric in Near IR|
I learned how to convert webcams to near-IR cameras by searching for DIY websites and videos online. This post is an amalgamation of what I have learned from this research and from using near IR cameras for many years. Here are a few websites that I found useful:
Wednesday, August 29, 2018
|Simone models her scary giraffe costume in visible and near IR|
There are many things that can be explored with a near IR camera. One of the more surprising things to observe is paper money. The back of $10, $20, and $100 bills have strips of near IR reflecting pigment that obscure the printing behind it.
|The reverse side of a $20 bill in visible and near IR|
|The reverse side of a $10 and $100 bill in near IR, notice almost invisible 100 on right|
The counterfeiting measures on the front of the $100 bill look very different in near IR. The inkwell disappears revealing the Liberty Bell. This happens in visible if you tilt the bill. The fountain pen and phrases from the Declaration of Independence disappear and the security ribbon becomes very faint.
|Obverse of $100 bill in visible and near IR|
|Visible and near IR image of a black plastic bag draped in from of space heater|
|My classroom with all the fluorescent lights on in visible and near IR on a foggy morning|
|The red LEDs of my binary clock and shining a remote control on my face in the dark with a remote control shining on it|
|South San Fransisco Bay Area from Saratoga, distant mountains only seen in near IR include Mission Peak|
|Colonial Peak looms over Diablo Lake in North Cascades National Park|
|Los Gatos High School pool in visible and near IR|
I hope I have piqued your interest in near IR imaging. Near IR cameras can be made by modifying a webcam. All you need to do is replace the IR cut filter with an IR pass filter. Another option is to purchase a Sony Nightshot camera and place a near IR pass filter over the lens. You can find used Nightshot cameras on eBay for less than $40. I will describe both of these options in detail in my next post. If you can't wait, there is a lot already posted on the Internet, search "DIY infrared webcam".
Friday, August 10, 2018
Dave Maiullo shows us his smoke ring cannon, adapted to the constraints of the room. Like most things, ring vortices look even better in slow motion.
Maiullo Smoke Rings
Bonus: Maiullo Dragon Voice!
Tuesday, August 07, 2018
At the "30 Demos in 60 Minutes" session, Colorado State's Brian Jones—director of The Little Shop of Physics and author of College Physics by Knight, Jones, and Field—showed us his secret to winning a tug-of-war.
Brian Jones Tug-of-War
I love it: so simple!. Two concerns:
Those once-ubiquitous single-use plastic bags may be an endangered species as voters outlaw them out of concern for the growing plastic islands and gyres in the oceans. It should work equally well with the thicker multiple-use bags that are now coming online.
I wonder if this will work as well on tile as it does on carpet. It clearly works like a charm on carpet. I guess I'll find out soon enough how well it works on tile.
Sunday, August 05, 2018
It is not rare when I spend time with my colleagues at AAPT meetings that I feel like I missed a memo somewhere along the line. If my head is swelling with overconfidence, mixing with my very talented, informed, creative, and knowledgeable colleagues puts me back in my place.
Such was the case when someone casually mentioned the use of Google's Science Journal during AAPTSM18. What? I have a bunch of Google apps, but I hadn't heard of Science Journal. Why not? I don't know. Sometimes I'm just not paying attention.
Anyway, Science Journal accesses sensors built into phones (or as we older folks think of them: smart phones or cell phones) and manages the data for easy use by phone users, such as students. Take a look.
Science Journal, an initiative by Google #ScienceJournal
I don't allow phone use in my class. Strictly and absolutely. Unless I invite exceptions. Phones are never far from students' hands. Given a green light, the phones can be out and about in no time. I'm not sure if I'll find a use for this in class. But at least I know it's there. Hmmm... experiment-based homework?
Tuesday, July 31, 2018
2018 07 AAPTSM18 Demo Show
Thursday, July 26, 2018
"It's not hoarding if your sh!t is cool."True. And this is the excuse I will give for keeping old vintage equipment that still demonstrates some physics. The same could be said for my father-in-law, a retired hospital mechanic that got to keep a lot of old equipment when it was replaced. He recently gave me a National Twin-Control Transformer, pictured below. It was used in the surgical wards to change the voltage of the lights (left dial) and cauterizing gun (right) from the 120 V wall outlet. I found a few more of these online for sale as interest pieces, luckily no one suggested actually plugging it in. There is an on/off dial at the top and what appear to be banana-type lead ports underneath each control.
The art deco style seem to be from the 1920s or early 1930s. The plastic shell is Bakelite, the first synthetic plastic for which the American Chemical Society named it a National Historic Chemical Landmark. One of its most common applications were casings like this for electric devices because it was very electrically resistant.
Monday, July 23, 2018
While most of us recognize that people come in all different shapes, sizes, colors and backgrounds outwardly acknowledging it is important in your classroom. In a time when many are feeling less welcome in our own spaces (work, home, country, etc) it is vital that we actively work to recognize marginalized groups in our fields and help to lift their voices.
On June 4th a new Twitter account @500QueerSci was launched with the purpose of bringing awareness of LGBTQ+ people working in STEM related jobs during the annual Pride Month. Their goal was to reach 500 personal stories and by mid July were at 630 biographies. People can submit their abbreviated biographies, pictures and social media links to be added to the catalog. The full list is found on their companion website 500QueerScientists.com.
The resource is amazing and as many have said when they first tweet their own featured biographies they wish such a thing had been available when they were young. It serves as a reminder to young LGBTQ+ people interested in science that they are not alone and that can be life changing.
I recently went back to the website hoping to find a search bar to type "physics" into so that I could have a list of many LGBTQ+ people with backgrounds or jobs in the fields of physics. I could not find one so I tweeted at @500QueerSci and asked:
@500QueerSci is there a plan in the works to make the stories searchable by field? I would love to be able to show my students some specific stories of 🏳️🌈scientists in related fields to what I teach.— Bree BarnettDreyfuss (@BarnettDreyfuss) July 13, 2018
They responded that such a feature was in the works but in the meantime offered to find such profiles for me. Below are the names and links they provided:
- Chanda Prescod-Weinstein
- Izzy Jayasinghe
- Giampiero Mancinelli
- Axiel Yael Birenbaum
- Nicole Ackerman
- Tzula Propp
- Shawn Cole-Woods
- Kelsey Collier
- Carlos Arguelles
- Aidan Robson
- Ana Barbara Rodriquez Cavalcante
- Beck Strauss
- Kerstin Nordstrom
- Tessa Carver
- Christopher Aubin
- Robert Newberry
- Jost Migenda
- Andrew Princep
- John Barentine
- Mackenzie Warren
- Katie Mack
- Ashley Spindler
- JJ Eldridge
- Stephen Lawrence
- Alysa Obertas
- Nick Geitner
- Andrew Welsh
- Georgia Squyres
- Whenever a particular field comes up in class, say astrophysicist, feature an LGBTQ+ person or person of color instead of whoever is at the top of a Google search list.
- "Profile a scientist" activities are already usually limited to exclude the few that everyone already knows about like Einstein or Curie or Tesla. If you're going to set restrictions for who they can't research you may find yourself just producing a list from which students have to choose. And look at that, you have a class set (or almost) of physics related names right up there! How convenient!
- You can present the list in its entirety, or the full website, for students to explore st their own pace. You can lead a discussion or offer reflection time for students to think about the featured scientists' paths through education and the hardships they may have endured for being LGBTQ+, why their visibility is important, etc.
- Make posters of the featured physics related persona biographies to display in your classroom or school all year.
- Feature an LGBTQ+, woman and/or person of color that is in the STEM field each week in your classroom.
Edit: I was able to add a few more resources I could not find the first time around thanks to recent AAPT plenary Frank Nochese:
The hashtag #ActualLivingScientists is used by all kinds of, well, actual living scientists, to share information about their work and why its cool. Several teachers print out some of these profiles to make displays in their classrooms or around
Heather Waterman @WatermanPhysics makes a daily doodle on her board about a scientists from an underrepresented group. I have a minor in art and I still don't know if I could draw a scene every day that was this good!
177:180 Marine Zoologist Mary J. Rathburn 🦐🦀#dailydatedoodle #womeninSTEM #WomeninSTEAM https://t.co/Y0WGcV4TCQ pic.twitter.com/bTcO6LWIdR— Heather Waterman (@watermanphysics) June 13, 2018
Wednesday, July 18, 2018
Let's say you you were into making solar ovens. Let's say that you decided a few years ago to make the best solar oven ever. Further, let's stipulate that you saw a nearly meter-diameter Direct TV antenna on the side of the road. An idea happened. You rushed to the local plastics store and bought highly reflective Mylar and glued it to the antenna.
Your solar oven was pretty amazing. While the hot spot wasn't super small, it was hot. Really hot. It can pasteurize a liter of water in 15 minutes.
And now you work at the Exploratorium and you think that you might bring it to work for grins. If you forget it in the back of the your Outback face up on a sunny day near the solstice, well, it can melt the molding in a fairly impressive way. I think I was lucky that my car didn't catch on fire.
You might be wondering how I could make such a mistake? I had a lot to carry into the Exploratorium, and the mirror wouldn't fit on the cart. I planned on coming back in a few minutes, but I got busy doing something else, and it slipped my mind. Coming back in the afternoon, I sat in the driver seat and looked into the rear view mirror.
If you want to make your own parabolic mirror, you can find some excellent instructions here.
Marc "Zeke" Kossover
Sunday, July 08, 2018
I give up. This post can now be read on my website: https://the-physics-well.net/its-not-easy-explaining-green/
This post was fine for more than 3 years, then I made the mistake of updating a broken link. That is when the malicious Blogger AI decided my post violated their malware rules and took it down. I spent a lot of time combing through, removing links and anything that might be setting off the Blogger AI. Nothing worked so I moved it to my own website. At this point I do not know if it will even allow this much. If you are reading this, I was successful.
What is most frustrating is that there is no way to contact a human being about this. Blogger has turned over their administration to a Skynet-like AI system that is ruthless and unforgiving. I suspect this is only a hint of what our future will be like. God help us.
Tuesday, July 03, 2018
I plan to start the activity by asking students what is necessary for an automatically deployed air bag for a dropped cell phone. They could work in pairs or groups and discuss the basics of the design criteria for a device that protects the dropped phone from breaking. I expect students to think about drop proof cases they may have seen commercially available that have enforced corners. Once they have made a list of the design needs groups/ pairs could share their individual lists to come up with a whole class list.
After their criteria has been established I would like to show students the original Honda parody video above. The original Honda video has been removed from their YouTube channel but the video is available on a few news sites. Since I can't find one with subtitles I'm not 100% sure its clean for the classroom but its probably safe since it was originally published on the official Honda page. Even on silent students can watch the video and observe his design process; it could be considered an advantage that they have to rely on the visual only and can't regurgitate anything they hear the engineer say. They will probably laugh at the final design but it will serve as a starting point for the next stage.
Before watching the video, or after, students can be given the shorter article about the parody video that summarizes it and includes stills from the video. Ask students to discuss if the Honda Case N meets all aspects of their design criteria. If their class list was missing something about the phone case being of a practical size they will probably want to add it now. This should lead to a discuss about additional criteria they might want to add.
At this point you can ask students to actually start brainstorming an air bag device on paper. This may include some conjecture and may not hold up to questioning:
"There will be this bag that shoots out here..."
"How will it shoot out?"
"Ummmm some kind of compressed gas..."
"Where will that come from?"
And to an extent that is completely okay. Students aren't going to be able to build a workable model like they do with the Crash Cushions project. This activity is not even necessarily focused on the ideas of impulse either but more on reasonable design criteria
I found this article about the spring loaded German design and made a pdf to share with students. The original video can be shared as well, although it is in German. I plan to ask students what is most important to that design and if it meets all of their design criteria. Students can discuss differences in their design and the German spring loaded design, which of their own design criteria it does not meet, etc.
The viral German spring loaded design is expected to go to Kickstarter soon to crowd fund enough capital to begin production. You could continue the activity with students by asking them which of their own designs they would help crowd fund (before showing them the German design). After they see the German spring loaded design you could ask students if they support it enough to fund it as well, hypothetically of course.
While I plan for this to be a substitute activity it does require the sub to be capable of playing online video clips if your students do not have one-to-one devices like Chromebooks. My subs are not usually capable of operating my projector nor are we a one-to-one school so I don't know how likely I will be to implement this in the next school year. I've summarized everything, including questions I would ask students in this teacher guide for the activity.
I would love to hear any one else's ideas for extending this activity below.