Wednesday, September 15, 2021

Bad Apple: A classroom skepticism quickie

Among the accepted truths of Watergate is that the Nixon campaign didn't need to do it. He was going to win the 1972 Presidential. There was no need to break into the Democratic National Committee offices; there was no intelligence that a Nixon campaign really needed. Nevertheless, break in they did. And Nixon eventually resigned as a consequence.

At the September 2021 Apple Event (California Streaming), the reality distortion field (RDF) was energized for a slew of new tech offerings. Among them, Apple Watch Series 7. The face of the watch was enlarged by a few pixels. But marketing is marketing. So to illustrate the significance of a few added pixels, Apple presented this image to demonstrate how much more text could be displayed.

The exercise is to show the image to students and have them tell you how Apple fudged this. Clearly, six or so more words appear on the newer model. The watch's screen only went from 44mm to 45mm (diagonal). Why so many more words?



What sorcery is at work here? With any luck, tech-savvy, skeptical teens will be able to knock a few holes in Apple's marketing RDF. Better still if they ever had to write a paper with a minimum page count requirement.

Should Apple have worried that without this dubious marketing exaggeration, Apple Watch sales would plummet, casting doubt on the future profitability of the tech giant? 

Given the facts in evidence, motivations and human nature, the Nixon camp still broke into those DNC offices in The Watergate.

Tuesday, August 10, 2021

Going With the Wind, A Twitter Story

Derek Muller started creating unique videos that are often related to physics and physics education in 2011 on his Veritasium YouTube Channel and website. I was a big fan from the start and have shown his Misconceptions About Temperature video to hundreds of teachers at my workshops. One of his recent videos, Risking My Life to Settle a Physics Debate, was very entertaining but I did not pay close attention to it. In it Derek recreates an accomplishment that was originally done by Rick Cavallaro and John Borton. In 2010 they drove their Blackbird vehicle directly downwind faster than the wind. This is sometimes abbreviated as going DDWFTTW. In a 10 mph wind the Blackbird reached a top speed of 27.7 mph, almost 3 times faster than the wind. This feat was well documented and explained at the time. But this begs the question, why did Derek Muller title his video "Risking My Life to Settle a Physics Debate"? Although there were a few people skeptical of the 2010 achievement, if you spend some time digging into the data and documentation, this skepticism fades quickly. Unfortunately, I was not one of the people who did their homework. I watched the video with an uncritical eye. When I read on Twitter that Derek had made a bet with a physics professor, I responded with a Tweet referring to other scientific bets.


Soon after that, the physics professor who had accepted the bet, Alex Kusenko, responded to my Tweet:

This got my attention. One of the principal subjects in an ongoing social media drama had responded to my Tweet. His confidence made me question my original acceptance of the DDWFTTW success, but I was still supportive of Derek's Blackbird ride in my response.

Using Galileo's famous but apocryphal quote was a little off-base considering that there was no question that the Blackbird moved. The question was whether it could go faster than the wind when going directly with the wind. Assuming that the force of the air could get it up to the speed of the wind, how could it continue to speed up in what would be a dead calm for the person on the Blackbird? How could it extract energy from the wind to add to its kinetic energy? Alex's response linked to his presentation explaining why he thought DDWFTTW was physically impossible. You can find his presentation online but it has been updated.

After reading Alex's slides I had more questions about Derek's Blackbird ride. It seemed plausible that the wind speed decreased rapidly while the Blackbird lost speed at a slower rate, allowing it to go faster than the wind temporarily as it slowed down. I analyzed the forces and realized that Derek had left out something important in his video. He never mentioned that for the wheels to be driving the propeller, there would have to be a force of friction from the ground that opposed the motion of the Blackbird. I sent Alex a reply that shows my growing doubt. The flattery in his response may have influenced my change of mind too!

I decided to pick a side and responded to one of Derek's Tweets. Although I don't regret sending this, I wish I had left the remark about investing the $10k out, it was arrogant. This Tweet is now pinned to Alex's account so I am still paying for it!

Alex contacted me after this Tweet to discuss a project with his educational platform Kudu.com. We have had several video conferences since then but they concern a project to create an AP Physics 1 course on Kudu.com. It will be free for high school teachers and students to use. Since these conversations are not related to this post, I will not mention them further. The above Tweet also drew the attention of Rick Cavallaro, one of the inventors of the Blackbird. I was unaware of the amount of skepticism he has had to deal with and his extensive efforts to to explain how the Blackbird works. He rightfully called me out on the $10k remark.

I received this Tweet while on vacation in Colorado. I did some reading about the 2010 DDWFTTW record and realized there was a lot more to this than the Veritasium video. I discovered that there was a lot of data to indicate that it had been done before. The question was, did Derek go DDWFTTW in his video? That is what the bet was about. The video shows Derek going into the wind with a telltale indicating that the direction of the wind relative to the Blackbird is front to back. That indicates he was going DDWFTTW. If it was from a sudden gust of wind then the Blackbird would be slowing down. This is what Alex was claiming. If it was being driven by the wheels powering the propeller, the Blackbird would be speeding up. This is what Derek was arguing. I realized that if the speed of the Blackbird could be measured, the bet could be settled. Unfortunately, they did not outfit the Blackbird with sensors to measure its speed in Derek's video. I noticed radial lines on the back wheels that could be tracked with video analysis. I decided to use the video analysis in PASCO scientific's Capstone software to measure the angular speed of the wheel using these lines. I work for PASCO scientific and have Capstone installed on my computer. I downloaded the video from YouTube and found the section where the telltale indicates it is going DDWFTTW. It was difficult to analyze because the video was shot from a moving vehicle causing the wheel to move around in the frame. I asked our technical support manager at PASCO scientific, Mike Paskowitz, if he had any ideas. He suggested I track the end of the rotating line on the wheel and the center of the wheel. Capstone could calculate the difference between these 2 points yielding the y component of the radial line on the wheel. A graph of the y-component as a function of time would be sinusoidal. I could use Capstone's analysis tools to fit a sine function to it. The angular frequency of the sine function would equal the angular speed of the Blackbird. This worked pretty well and showed that Blackbird was speeding up. Because of the poor quality of the video, I hedged my conclusion when I Tweeted out my results.

I posted a Tweet showing the video and complained about the lack of data on Derek's Blackbird ride. Derek responded with an offer.

He also direct messaged me with an offer to send some high resolution video of his Blackbird ride.

I downloaded the video and we had a nice exchange of DMs. He even started following me on Twitter!

Before I could get to the analysis, Alex conceded the bet that very day. I don't know if the video analysis was the deciding factor but it did play a role. I was relieved because the video Derek sent me was not great for video analysis. The lines on the wheels were too blurry for the auto-tracking feature of Capstone to work. It is a lot of work do analyze 120 fps video manually.

I enjoyed the rest of my time in Colorado and put the Blackbird out of my mind. After returning home, Rick Cavallaro tagged me on this Tweet with a link to a video by Engineering with Rosie. It did a great job of explaining how the Blackbird could go DDWFTTW.

There were some things about the Blackbird going DDWFTTW that I had trouble explaining. For the Blackbird to speed up it needed a source of energy. If the source of energy was from the air, it would have to slow the air down to extract energy from it. But for the propeller to provide a force of thrust, wouldn't that speed the air up? Rosie's video explained this very clearly. The sketch from her video below shows how the air can speed up from the reference frame of the Blackbird yet slow down relative to the Earth's reference frame.

Rosemary Barnes' sketch expertly explained starting at 5:37 in her video

Another thing I had trouble explaining was how the Blackbird worked as a machine. Machines are used to do work on something. The work you put into a machine is always more than the work you get out of it. I thought the Blackbird was violating this because I viewed it from the perspective of the ground doing work on the wheels as the input work and the propeller doing work on the air as the output work. I realized I had this backwards. The Blackbird is a machine that uses energy from the moving air to do work on the Earth. I sent Rick a Tweet thanking him for recommending Rosie's video.

And he replied asking me if I had changed my mind. I answered in the affirmative but was still struggling with how I would explain the Blackbird to a high school physics student. That is always a good test of understanding.

Rick then sent me a Tweet with a link to a document he had recently written and a link to video of a talk he gave in San Francisco in 2017.



It is easy to see that Rick is generous with his time to help people understand how the Blackbird works. You can also tell he is a little peeved at Alex. I had seen the video before but the document gave a very detailed example of how the Blackbird can go DDWFTTW. If I was still teaching I would invite him to give a talk to my physics students. I then got around to re-doing the video analysis using the 120 fps video Derek sent me. It was still too blurry for auto-tracking to work so I analyzed less than 2 seconds of motion. The data came out much cleaner and still showed the Blackbird speeding up while going DDWFTTW.

Here is the video from the above Tweet:

 


I was surprised when he sent me a direct message the next day with an offer to talk on the phone.

I enthusiastically agreed and benefited from his knowledge and ability to explain things. He also listened to my thoughts and helped clarify them. I expressed my disappointment in some of his comments about Alex's concession of the bet. However, I told him I understood his impatience with those of us who were skeptical of something that had been well-documented in 2010 and had a sound foundation in the laws of physics. It is similar to when those who helped land people on the Moon hear from the idiots that say it was a hoax. The difference is we sought out the facts and admitted we were wrong.

Later that day Derek released his sequel to the his first Blackbird video. In it, Derek takes responsibility for the shortcomings in the first video including an incomplete explanation and lack of data. That was big of him but as I stated earlier, the primary shortcoming was the lack of effort to research on the part of those of us who expressed skepticism. The first video and the information posted elsewhere about the 2010 record-breaking run by Rick Cavallaro and John Borton were sufficient to win the bet. However, the second video is so good that I am glad Derek felt it was necessary to make. I remember feeling a little better when the video revealed that Bill Nye also was skeptical. He showed some of that skepticism earlier in a Tweet:

In the video Derek shows an email from Bill Nye where he says "I am pretty sure the inventors of the Blackbird are fooling themselves, or us, or both --- and, I was not thinking critically when I watched your video." This reminded my of my Tweet quoting Feynman about how easy it is to fool yourself. Here was a former engineer who also had convinced themself that the Blackbird could not go DDWFTTW. I wanted to link to this part of the video but when I watched it again, the Bill Nye email was gone! I started to doubt that I had seen it when I did a search and found the Tweet that preserved the email in a screen capture. Apparently Bill Nye asked Derek to remove this from his video. That is too bad. Being wrong and showing when others are wrong is crucial for the advancement of science and engineering. A person who goes by the moniker "The Science Guy" should not hide their mistakes.

Another part in the second video that stood out for me is the video analysis of Derek's Blackbird run. They edited the video to track the center of the wheel so that it remains fixed in the frame. They added 2 color bars to show the rotation, making it easy to see that the Blackbird is speeding up while going DDWFTTW.

 


At 8:43 in the second video Derek mentions that it was "someone on Twitter" who suggested doing video analysis. I thought that could be me so I asked Derek about it in a DM.


He confirms it, sort of. So I can claim I was mentioned in a Veritasium video. One more thing crossed off my bucket list! Now all I have to do is find the time to make the model of the Blackbird that Xyla Foxlin describes in her YouTube video. Click on the "SHOW MORE" link at the end of the video description for details. Thanks for reading my self-indulgent story. It is over except for the notifications I keep getting whenever someone likes one of the redundant replies to my Tweet pinned to Alex Kusenko's Twitter account. At least onr part of it never ages: "The first principle is that you must not fool yourself — and you are the easiest person to fool."- R. Feynman






Monday, August 02, 2021

POTU Evolution Part 1: From California to Rio Americano

Encore Post: Originally published February 21, 2020—in the last days of The Before Times. Sigh.

UPDATE 2/23/20: Extant course chart added.

We plan to launch our Physics of the Universe (POTU) course in 2021-22. Physics of the Universe is the physics portion of the three-course model for Next Generation Science Standards (NGSS) implementation. California is where I live and work; Rio Americano High School is where I've taught physics since 1986.

Our plan is to discontinue Physics as it has existed at the school since its inception in the 1960s, and replace it with POTU. We will continue to offer AP Physics 1 and AP Physics 2 (when demand exists). I plan to retire at the end of the 2022-23 school year, so the course will evolve considerably after I'm gone.

Here is a pie-chart representation of the course as it exists, in terms of the unit topics.


But August of 2021 is coming, so there is a course to create. The POTU Evolution blog posts will chronicle my development process for the benefit of both of my blog readers.

The state of California has developed a framework for the three-course (Biology, Chemistry, Physics) implementation of NGSS. (Feel free to read it real quick. I'll wait.) Physics of the Universe is divided into six segments.


As this course-development project began, my first step was two turn those six segments into twelve units. And I felt I needed to move the nuclear unit. So already, some entropy is working its way into the pie chart. Notice that where I broke one segment into two or three, I maintained color fidelity to the framework's six segments.


As I read deeper into the framework, it became clear that some subsegments were more equal than others. As I began mapping out a day-to-day schedule, my concept of the course took this shape. It's not even trying to appear appealing anymore. But that's not what's important. There are 180 days to plan, and they're not going to plan themselves.


That's probably enough on the planning for now. I'll post unit schedules as I develop them. It's hard to overemphasize how drafty these visions are right now. But they are preliminary drafts at best.

A few additional details: the principal would like our POTU course to be accessible to freshmen. Given that our district is all-in on Integrated Math, any algebra necessary in the course will need to be taught in the course.

We will be adopting textbooks next year for all science courses. Our last adoption in physics was in 2008. POTU textbooks are... largely still in development. I think Conceptual Physical Science would work nicely for NGSS 3-course Physics and Chemistry, but we'll see what the adoption options are in 2020-21.

Thoughts? Ideas? Advice? That's what the comments section is for. I'm keen to hear about what you're doing as NGSS and new assessments appraoch.

Tuesday, July 20, 2021

One document format to rule them all

When the pandemic hit and schools closed down, I was knocked on my backside pretty hard in many ways.

One thing I found I needed to do—and quickly—was to convert my student curriculum documents into Google Docs format so that I could deploy them in Google Classroom. I had virtually no experience in Google Docs or Google Classroom. And I was facing four preps: Physics, AP Physics 1, AP Physics 2, and Conceptual Physics. A considerable mountain of work loomed.

I'm confident that my colleagues handled the transition better than I did. But I did my best. I transformed many of my documents (Apple Keynote files/PDFs) originally intended for printing and photocopying to Google Docs format for use in distance learning. I leveraged features that made the documents both student and teacher friendly. 

When school morphed again into "hybrid" (which will likely go down in history as the worst model of instruction ever implemented), the Google Docs fell a bit short. Certain elements that made the Google Docs useful for distance learning made them difficult to use for in-person instruction. I could use the old PDFs in-person and the new Google Docs for distance, but multiplying that load by four preps made that unpalatable.

A few modifications made the Google Docs versatile enough to be used successfully for both in-person and distance learning. I refer to these as Print-Friendly Google Docs. One file to rule them all. Precious to me!

In the summer of 2020, I whirled Dervishly to convert my Lessons of Phyz products from PDFs to Google Docs because if I needed Google Docs for remote teaching, so would everyone else. This summer, I am working feverishly to transform those Google Docs to Print-Friendly Google Docs because who knows what's next?

Breakthrough: Ideas that Changed the World, How Earth Made Us, Our Planet, One Strange Rock, and Pandemic are done. Everything else remains in progress or in the queue. 

And at long last, I finished a new product! First real, new item since Pandemic [Netflix series] in March, 2020. I branched out into chemistry with Jim Al-Khalili's BBC series, Chemistry: A Volatile History. I'll probably work on David Pogue's chemistry NOVAs next. This item is the first to be offered as a Google Drive digital download. No PDFs; no Zips. I foresee all my new products being posted to TpT that way.

Digital document evolution. I do not foresee an end to that.

Tuesday, April 13, 2021

Teeeeter Totr

Just a quick balanced torque puzzle. It's really a test of whether or not one truly accepts the concept of center of mass.

Nothing exotic going on. The meterstick is uniform. Sufficient information is provided to solve the puzzle. It can be confounding to students.

Teeeeter Totr - HTML export | movie export

UPDATE: Among the many things I can count on in life is that virtually any mechanics demo I might share here has already been done better by the inimitable Dan Burns. For example:

Sunday, April 11, 2021

RT;DL Pixel Peeping

Screens. When I was in school, screens were reflective white, flat curtains pulled down from retractible rolls when the teacher was going to show an educational film on the reel projector they shared with the other teachers at the school.

At home, screens were cathode ray tubes in which a spray of electrons, steered by magnetic fields and attenuated by a shadow mask, struck red, green, and blue phosphors. The high-pitched noise given off by the electronics of a CRT TV monitor create physical pain in modern-day students. TV watchers of a certain age somehow tuned that 10 kHz+ whine out.

Today, screens are everywhere, and virtually all are based on light-emitting diodes. But the RGB nature of color imaging remain. That's what this activity is about.

Color mixing and pixel geometry. Surprising enough and instructional enough to be worthwhile.


Pixel Peeping Student Document (Google Docs copy link)

Pixel Peeping Magnifier Observations - HTML export  |  Movie export
(media links are included in the student document)

The PhyzSommelier says this activity pairs nicely with

PhyzLab Springboard - Fun With Colors (Google Docs copy link)


Saturday, April 10, 2021

Thursday, April 08, 2021

In the George Floyd trial: Audio Pareidolia

Humans are so good at finding patterns, we often find patterns where none exist. This phenomenon is referred to as pareidolia. 

Add to this the power of suggestion, and things get even more interesting. The back masking panic was fueled by audio pareidolia. As was EVP: electronic voice phenomena, a means by which ghost hunters fool themselves and others.

I made a presentation on the audio version of this phenomenon and deployed it during our unit on waves and sound.

It was all good, wholesome, laughable fun. And then it showed up in the trial of Derek Chauvin. I have updated the presentation to reflect this latest incident. I placed it at the vary end so that by the time you get there, you'll recognize exactly what's going on.

Back Masking (HTML export)

Thursday, March 25, 2021

Polarized Black Hole Image

It's probably irresponsible for me to post this wee package that might deliver more questions than answers. Nevertheless.

Saturday, March 20, 2021

RT;DL Physics in the Fountain of Fizz

The Diet Coke Mentos geyser made a big splash in popular media before social media was a big thing. I was keen to incorporate it into my curriculum, but needed a content-based hook. Mythbusters (among others) focused on the chemistry of the spectacle. That was entirely cromulent: it's the engine that drives the demonstration. 

But I teach physics. And there's plenty of physics to exploit. Between the beginning and end of the eruption, some quantity of mass is ejected. Mass flow rate? Check. The fizz emerges from the bottle with some speed and reaches some altitude above the launch point. Energy conservation? Check. Determination of muzzle speed from maximum height? Check. Total energy dissipation approximation? Check. Power approximation? Check.

My school is a 1960s-era low-slung, sprawling campus. Determining the maximum height of the eruption is non-trivial. Most buildings top out at about three meters. We do have an accessible tall (~6 m) wall made of cinder blocks as part of our gymnasium. So that's what we settled on.

Initial mass is measured. Video is captured. Final mass is measured. The video is analyzed. Calculations are made.

Fountain of Fizz Student Document - Google Docs copy link

Fountain of Fizz Observations - HTML Export | Movie Export

Media links are included in the student document. The movie export is included for use on devices that struggle with the HTML export.