Tag: physics

Alpha Magnetic Spectrometer

The BBC has an excellent article on the Alpha Magnetic Spectrometer (AMS) launched on the second to last shuttle flight to investigate the origins of the universe. NASA’s page is giving regular updates.

What’s nice is that the basic physics of magnetic spectrometers, where magnets are used to deflect the motion of charged particles, should be accessible to middle school students once they get into electricity and magnetism.

How the AMS works. Image from CERN via the BBC.

Transition Radiation Detector determines highest-energy particle velocities
Silicon Trackers follow particle paths; how they bend reveals their charge
Permanent Magnet is core component of AMS and makes particles curve
Time-of-flight Counters determine lowest-energy particle velocities
Star Trackers scan star fields to establish AMS’s orientation in space
Cerenkov Detector makes accurate velocity measurements of fast particles
Electromagnetic Calorimeter measures energy of impacting particles
Anti-coincidence Counter filters signal from unwanted side particles

— Amos (2011): Alpha Magnetic Spectrometer to go on Endeavour shuttle on the BBC.

For additional information, that really gets into the nuts and bolts, you can go CERN’s technical site or get more general info at their public site, which has a wonderful set of videos and animations.

If a tree falls in a forest and no one is there to hear it, does it make a sound?

I get this question occasionally from my students, and the answer is, of course, that it depends on how you define the word “sound”. Jim Baggott, on the Oxford University Press blog, goes into more detail about the roots of this philosophical conundrum, and makes the parallel to quantum physics.

This tree fell in the woods in Little Rock. Did it make a sound? Depends on who you ask.

Physics and philosophy are a dangerous pairing, particularly since if you know enough about one to speak intelligently about it, your probably way out of your depth in talking about the other. Just because you’re an expert in one field does not mean you’re going to be an expert in another. This is especially true of physics and philosophy, which approach the world from such different perspectives and use such different languages: to a physicist, “sound” refers to the vibrations in the air, while a philosopher might argue that “sound” only exists in our minds.

Philosophers have long argued that sound, colour, taste, smell and touch are all secondary qualities which exist only in our minds. We have no basis for our common-sense assumption that these secondary qualities reflect or represent reality as it really is. So, if we interpret the word ‘sound’ to mean a human experience rather than a physical phenomenon, then when there is nobody around there is a sense in which the falling tree makes no sound at all.
— Jim Baggott: Quantum Theory: If a tree falls in forest…

Rube Goldberg music video

The group OK Go set up an excellent Rube Goldberg machine for their music video, This Too Shall Pass. Thanks to Sage B. for pointing this one out to me. She’ll probably get to see it again next year when we get into physics and electricity and they need a little inspiration for their own machines.

Last year I used Honda’s The Cog advertisement, which is much simpler (and shorter) than OK Go’s.

Pumpkin Chuckin

Photo by <a href='http://en.wikipedia.org/wiki/File:Pumpkin_chucked_from_trebuchet_in_ohio.jpg'>Kevin D. Hartnell</a>.
Photo by Kevin D. Hartnell.

Mr. B’s put me on to the World Championship Punkin Chunkin Association, which has an annual competition. There’s a Discovery Channel program about it too.

Although my head-of-school is not partial to us throwing food around, a trebuchet would make a great project for physical sciences next year (Year B).

Resurrecting the greenhouse

Two years ago, the middle school’s flagship project was to put up a fully functional greenhouse (using this design). It took all year but we did it. On the way, we got to practice geometry, mapping and construction, while learning and growing plants and studying soil profiles. It was so successful that, with our spring plant sale we broke even on the entire project.

Last year, however, the greenhouse was somewhat neglected. My plans to add an automatic window opener, which would have been a wonderful tie-in to our electronics and Newtonian physics studies, did not work out; we just did not have the time. We’d taken the plastic covering off, so only the bare, forlorn PVC frame was left standing around a plot of waist-high weeds.

Though I could not have predicted it, this year we have a strong core group of students who are highly enthusiastic about resurrecting the greenhouse and making it work. My suggestion was that we try to grow produce this fall that we could cook in December when we do our Dinner and a Show. Well, two weeks in, they’ve already put together a menu plan, weeding is well on its way and I’m being harassed to hurry up and arrange a trip to Home Depot. The excitement is so infectious that another student has volunteered to bring in his electric weed-whacker during the immersion. It’s amazing!

I’m having the hardest time not butting in. There is a beauty in seeing a well oiled machine executing a project or solving a difficult problem. But there is another even more wonderful aesthetic visible in a the birthing struggles of a nascent team. The forward motion of infectious enthusiasm is pulling puzzle pieces into its wake, and the pieces just seem to click into place when the time is right. I have to keep reminding myself that my job is to prepare the environment and let the kids do the rest.

Timeline of life

Timeline of Life on Earth.

This year the theme is life. My central organizing structure is the timeline of life on Earth. I plan to link all of the discussions of taxonomy, phylogeny and genetics to this timeline over the course of the year.

The timeline above will be the first lesson. As with these things the trick is deciding how much detail to keep in and how much to keep out.

What I like is that it gives the general overview of when important things happen while leaving a lot of space for students to investigate. Most of what we’ll be seeing this year happened in the Cambrian and this timeline conveys that this is a very small part of the whole history of life. In fact, it’s only when we cover the biochemistry of genetics that we will be talking about the origins of life.

From the Exploring Earth's Origins website.

The website Exploring Life’s Origins has a great timeline. It also has some really neat sections, with very useful videos, on the formation of protocells and the origin of RNA on the early Earth that lead to life as we know it.

The Magnetic Field?

The one thing I left out that I’m still conflicted about is the Earth’s magnetic field. Recent research indicates it has been around since 3.2 billion years ago and its presence or absence may have had profound effects on life.

The Earth's magnetic field protects us from the solar wind. Image from NASA.

Having a magnetic field protects the Earth from the charged particles spewing out of the Sun, the solar wind. This makes life on land a lot easier since the solar wind’s particles are quite damaging to DNA. However, prior to the magnetic field forming all this damage to DNA may have also accelerated mutation and thus evolution.

Segway lessons

From playing with robots we tried an actual application of robotics. We had the Segways 101 course at the St. Louis Science Center.

The lesson itself was fun, with an entertaining video of people falling off Segways. They also had a little obstacle course to let you try doing all of the things the video told you not to do (but most of it was for the more advanced class).

Afterward, we discussed the fact that this too was robotics and a pretty advanced application at that. We did not talk much about how the Segways were supposed to revolutionize urban transportation but students did recognize the fact that aesthetics were a major impediment to their broader adoption.

The price was a bit steep however, and I’m a little conflicted about if it was worth it.