Full Length Mirrors

I saw this demo at last summer's (2009) meeting of the American Association of Physics Teachers. It was part of a really great presentation by Dr. Peter Hopkinson. The basic question was, "How large does a mirror need to be to see your whole body?" The concensus response from the audience of physics teachers was, "It depends on how far away you are from the mirror." As it turns out, the wisdom of crowds failed this one.

I managed to score a "full length" mirror from Target for $5. The mirror is one of those cheap ones you put on the back of a door and is nowhere near my height, it's about 2/3 my height. Yet if I mount it appropriately I can see my whole body at any distance. Just watch the video below for full details. Oh, and if you ever get a chance to see Dr. Hopkinson speak at a meeting you should jump at it!

Sound Science Part 2 - Recreate sounds with Audacity

This is one of my favorite demos involving sound. In this demo we use a computer to recreate the sound of a beaker being struck with a pencil or a ruler. All you need is Audacity, which is free. The first part involves the use of the FFT function to analyze our sound and then we use the tone generator to build the sound one frequency at a time.

While sounds are composed of a combination of different frequencies there's more to them than just that. You also have to look at the initiation and the ending of sounds. Specifically for our beaker you have to look at how the various frequencies decay. We can use another feature built right into Audacity to get close enough to the decay as well by applying the "Fade Out" effect several times.

For full instructions, simply watch the video below. If you want detailed written instructions surf over to my page on Probeware on a Budget.

Physics of Superheroes

I've been using pieces of James Kakalios' Physics of Superheroes for a couple years now. This year I'm using it a bit differently. Last summer it was one of two books my honors physics students could choose from for summer reading. Why should english teachers have all the fun? In the Physics of Superheroes Dr. Kakalios doesn't try to explain why superheroes have super powers, instead he focuses on two different questions.

The first is, what are the implications of these powers? In the video below I go through his idea of how fast Superman is moving when he "Leaps a tall building in a single bound". Dr. Kakalios also ask questions like, "Would Ant Man be able to hear us when we talk?"

The second is, if we allow heros to have super powers would they be able to do the things they are shown to be doing? For example, if the Flash can really run as fast as he does could he in fact run across water or up the sides of buildings?

All of the questions and examples used are written from the standpoint of teaching basic introductory physics. His examples are great and my students really enjoy this approach to learning. The book is now in it's second edition and I have to say I'm happy with the changes that were made.

For extra-credit I offered my students the opportunity to write some superhero physics. For more on this or to see the outcomes just go to our class page. They are supposed to be done by the end of Christmas break (2009-2010).

Here Comes Science - Music To Teach

So, maybe I'm living under a rock, but I finally got around to checking out They Might Be Giants' Here Comes Science. I heard about it when it first came out, but dismissed it as being aimed at elementary aged kids. Then I finally got around to listening to an old Science Friday episode sitting on my iPod that featured the collection. While listening I went to Amazon to buy the MP3 album but then Ira mentioned the animations that come on the second disk. I went over to YouTube and sure enough many of the videos are there. Below you'll find the song The Elements. By the time Science Friday was done I'd already ordered my copy. I can't wait to share it with inflict it on my students.

For more music to teach with you might want to check out AstroCappella.

AstroCappella is a marriage of astronomy and music, developed by astronomers and educators and professionally recorded by the rocking a cappella group The Chromatics. Many of the songs, activities, and background science materials are freely available on their site.

Tracker for Video Analysis

I've blogged about Tracker before, but I have to say yet again that it totally rocks. I have this video clip that I use with my students every year of a student jumping as high as he can. Joe, the student, does the predictable, he lifts his legs and arms while in the air.

Traditionally I've had students track the motion of three points on Joe. His head, torso, and feet. We've already talked about the acceleration due to gravity near Earth's surface so I ask them why the acceleration of the different body parts is not -9.8 m/s/s. I also make them explain why Joe's torso is closest to -9.8.

Well Tracker allows us to do one better. We can track all of Joe's body parts and then Tracker will plot the center of mass for us. I used a table (from Oregon State) that I originally saw on the Dot Physics Blog for the distribution of mass in bodies. I ended up finding the acceleration of Joe while in the air to be -9.824 m/s/s (about 0.18% error).

Tracker is free and works on Windows, OS X, and Linux.

Podcasting on iTunesU

I applied and was invited to submit podcasts to the MI-Learning section of iTunesU. My main focus will be demos I use with my physics students. This way if they miss class when I do a demo they don't have to miss it completely.

Additionally I want to make sure my videos can be used by other educators who might not have all the right equipment to do demos or who might not know how to do them. I will be doing some videos intended to teach other teachers how to do various demos in class. Such as the Lasarium shown below.

You can find all of my Democasts at iTunesU, at Blip.tv, or the Archive.org.

Sixty Symbols - New Physics Videos

By now you've probably seen the Periodic Table of Videos produced by folks at the Univeristy of Nottingham. If youhaven't you really should check it out. But you may not have seen their Sixty Symbols videos.

In thier newest series they take sixty physics symbols/concepts and have created videos explaining what they are and what's cool about them. Below is the highlight reel. Check it out.