Dizzying dance demonstrates dynamics

Rotational dynamics, specifically. But I was going for alliteration in the title.

A different staging of this performance floated into my Facebook feed yesterday, and my jaw dropped. And it's not that I don't get out much. It's that this performance is jaw-dropping. And of course it's a beautiful synthesis of artistry, athleticism, physics, and practice. I don't even understand how a human can do this with functional semi-circular canals. Watch for yourself.

Angelica Bongiovonni - 34th Festival Mondial du Cirque de Demain - Paris


So in a #FirstWorldProblems moment, deciding to post this gem to the blog led me down bit of a rabbit hole. The video was locked into Facebook. I don't yet know how to rip videos from Facebook. YouTube, yes. Facebook, no.

The Facebook video linked to the Dance.com Facebook page. That didn't help. Neither did going to Dance.com, itself. The Facebook video didn't even mention the dancer's name. No surprises there. The comment count was in the thousands. Nevertheless, I began poring over the comments and found the dancer's name in a reply to a comment.

Off to YouTube. The dancer had a channel but the channel did not include this performance; it was sparse and seems to have been abandoned. She's apparently too busy dancing to maintain a YouTube channel.

So a general name search ensued. Adding "Cyr Wheel" didn't help. (Yeah, I didn't know it was called a Cyr Wheel. either. You can actually learn things from search results.) I couldn't find the video I saw on Facebook.

But I found the one posted above: Same routine; different performance. I don't see a simple "in" to an engaging paper and pencil companion lesson. But the video can stand on its own. Whenever I show such a thing in class, I verbally admonish my students that they must be thinking about physics as they watch.

One thing Angelica Bongiovanni did post to her wee YouTube channel was a short blooper reel made in preparation for a different routine.

I love the poster frame that shows up for the embedded video. That's the still you'd hope to capture if you were photographing the performance.

Hewitt-Drew-It! Force Vectors on an Incline

In this screencast, Paul Hewitt analyzes forces acting on a block on an inclined plane, leading to forces on a block sliding on a curved surface.

Hewitt-Drew-It! Force Vectors on an Incline

Hewitt-Drew-It! Force Vector Diagrams

In this screencast, Paul Hewitt extends Jim Court diagrams, identifying forces on a suspended, then falling ball.

Hewitt-Drew-It! Force Vector Diagrams

Hewitt-Drew-It! Nellie Hanging on Gym Ropes

In this screencast, Paul Hewitt shows two different ways of solving vector problems; resolution of vectors and the parallelogram method. He also shows a pulley problem.

Hewitt-Drew-It! Nellie Hanging on Gym Ropes

Hewitt-Drew-it! Nellie's Rope Tensions

In this screencast, Paul Hewitt explains how vectors are used to figure out forces and equilibrium. Paul uses a parallelogram rule to find resultant tensions.

Hewitt-Drew-It! Nellie's Rope Tensions

Hewitt-Drew-It! Equilibrium Problems

The Hewitt Drew It! screencast series continues with Equilibrium Problems. Hewitt works out a few number puzzles relating to the scaffold scenario discussed in the previous episode.

Hewitt-Drew-It! Equilibrium Problems

Announcing the "Hewitt Drew It!" screencast series

Conceptual Physics author, Paul Hewitt, has posted the first in a series of new screencasts. Each screencast is devoted to a specific topic. And each was written, animated, and narrated by Paul Hewitt, so the physics is correct and the content is accessible to virtually everyone.

These are all-new screencasts produced in a style familiar to those who have seen the popular Khan Academy videos.

The first Hewitt Drew It! screencast is about The Equilibrium Rule and tells the story of how Hewitt got "roped" into physics in the first place.

Enjoy!

Domino Chain Reaction

The usual caveats apply: I miss more than I see, and this one's been around for a spell.

Good, clean, unstable equilibrium, amplification fun nonetheless.



Hat tip: Fred Bremmer (one of the few people I literally look up to in the world).

"Honda Cog" in the classroom

I've found that one  good place to drop the classic "Honda Cog" ad into the physics curriculum is amid our lessons on energy transfers/transformations.

Those lessons begin with step-by-step analyses of a pole-vault and the firing of a toy dart gun (I'm a big fan of old-style dart guns).

Then we look at the Honda Cog ad.



First we watch it without interruption. Then we watch it with analysis. The video is paused, we discuss, then move on to the next pause-worthy event. There are openings to discuss energy transformations, equilibrium, Newton's third law, balanced torques, and more.

The one segment that students reject is the wheels rolling uphill (0:25-0:30 in the clip). They know that's fake.

So it's a good idea to have a Sargent-Welch Variable Inertia Kit (WL0707D) handy.

The intended use for these discs is to adjust the inner mass balls so that one disc has high rotational inertia and the other has low rotational inertia. The you race them down an incline. If students are unaware of the interior configuration, you've run a nice discrepant event.

But our purpose here is different. We need just one disc. Load the mass balls as shown so that the disc will behave like a Weeble.

Put the disc back together and set it in unstable equilibrium on an inclined plane. A slight disturbance will set it in motion—up the hill!

Entertaining equilibrium

If this guy's not a Libra, I shall renounce my faith in Zodiacal Astrology.



Wait: I have no faith in Zodiacal Astrology. Durn.

But what a lesson in balanced torques! And a nice soundtrack, too. The Hebrew of the video's title translates to "Amazing Performance and Power Balance," according to Google Translate.

Your assignment: make a clever number puzzle (standard physics numerical problem) out of this.

Hat tip: Marion Gribskov (my distinguished Rio Phyz predecessor).

Good solution or all wet?

From Britain's Orange:

A bus company in China has launched a new 'drive safely' campaign - by hanging big bowls of water next to their drivers.

The Longxiang Public Bus Company in Changsha, Hunan province, says drivers must drive gently to avoid spilling any water.

Bus drivers are expected to ensure the bowls are still full when they finish their shift, reports the Xiaoxiang Morning Post.

And the company warns drivers that CCTV footage will be studied to make sure they do not top up the bowls with water.

"Passengers often complain that sudden braking and bad driving makes them really uncomfortable on the buses," said a spokesman of the company.

"Hanging bowls of water in the driver's cab will discourage them from making any jolting starts, sudden braking or bad turns."

Is this a clever application of inertia and fluid dynamics? Or is it more show than go? (Notice the bowl is arranged as a pendulum rather than being fixed to the body of the bus. Curious.)

Spot the physics

My buddy and fellow skeptical photographer, Scott Hurst, sent this along.



I see physics. And I see pain. But mostly... WOW! It's 5:38 of your life you can't get back. Trust me; you'll be OK with that by the end of the clip. Don't forget to breathe!

If the video embed above doesn't work for you, click here. I hope to see more from master Danny MacAskill.

UPDATE: No, I couldn't leave "well-enough" alone. You know how I am. Here's a worksheet you can use as a classroom lesson to accompany the video clip. Can you write a better one? Of course! If you teach physics, you'll be keen to generate some estimation-based calculations. So have at it. Think of my lesson as a mere introduction to the video.

Best. Commercial. Ever.

And it never aired on TV, as far as I know. It's the best Rube Goldberg machine I've even seen, though better ones may be out there. (Pyromaniacs will certainly prefer this one.)

According to the lore (not all of it verified), the 2-minute sequence cost over $6E+6, was months in the making, required the dismantling of two of the six hand-built Honda Accords, and the first 605 takes didn't "just work." But enough of my jibber-jabber. Watch the Honda Cog ad.



"Simple," you say. The battle scenes from Lord of the Rings made better use of CGI. No doubt. The punch line is that there was no CGI or trick photography used in thise sequence. It all happened pretty much as you see it.

Snopes.com has a pretty thorough page detailing the backstory. London's Daily Telegraph has an in-depth story. There's even a The Making of Honda Cog video companion to the ad.

At two minutes, it's too expensive to run on TV. Honda seems to have hoped for viral distribution. I'm happy to join the party (if a wee bit late). Any big corporation that wants my services as a shameless shill can have them free of charge if they produce an ad as good as this one. Maybe something with magnets.

I've added it to my Web Video page, but I do not--as yet--have a corresponding lesson presentation or worksheet for it.

Thanks to NCNAAPT Webmaster, Tim Erickson, for turning me on to this groovy vid. It's over four years old, but I would have missed it completely without Tim's link on the NCNAAPT page.