Relativistic Greek tragedies

new-age-oedipus-rex

A re-imagining of Oedipus Rex by one of the students in my ‘Revolutions in Physics’ course. Finally got around to the scanning and posting part!

Friction

couple of quick links that I’ve already shared with my students in intro mechanics, and that you readers out there might enjoy:

One, on how we don’t really understand friction completely yet, is from Physical Review Focus, and is written by David Ehrenstein of the American Physical Society.
TO SLIDE OR NOT TO SLIDE
It’s no surprise that a block sliding across a table is slowed by
friction, but for small enough crystals, theory and a few
experiments suggest that frictionless motion may be the norm. Now,
in the 19 September Physical Review Letters, a team of researchers
pushing nanometer-sized metal blocks across an ultra-clean
graphite surface reports that some of them skate freely, while
others resist. The results support a theory that friction arises
only when extra atoms get trapped between the surfaces. This insight
into the origins of friction may be important for researchers
developing nanoscale machines that include sliding parts.

Dirk Dietzel et al., Phys. Rev. Lett. 101, 125505
Link to the paper: http://link.aps.org/abstract/PRL/v101/e125505
COMPLETE Focus story at http://focus.aps.org/story/v22/st10

The other is a video of a Mythbusters episode on exactly how difficult it is to separate two intervowen phone-books. It’s kinda amazing. Same principle as a gecko: surface area increases friction tremendously!

Enjoy!

Taking a deep breath …

It’s the end of the summer for us, finally, done, school starts on Monday, the leaves are beginning to fall, and jackets are definitely needed, syllabi are being written, the students are arriving on campus, all that.

I am looking forward to teaching an introductory mechanics class based on Chabay and Sherwood’s Matter and Interactions perspective/textbook. I like this perspective very much, but still haven’t figured out how to make it mine. I’ll be blogging about it as the term goes, but in quick summary, here’s what the class looks like:

It is a ground-up, computational take on mechanics. We talk about matter as composed of atoms, and then say that that first and easiest way to model the behavior of *all* matter is through interactions between them (forces). The properties of forces are first studied through kinematics — that is, looking at motion resulting from forces. And here is the most important jump — we study a variety of forces, with some analytical work, but almost immediately get into coding up these forces on the computer and visualizing their effect. We use VPython (visual python) which is both freely available and well-suited to this course, to do this. And we see how far we can get in 4.5 weeks on this (yes, this is Carleton, that’s all the time we get).

How far do I expect to get? Last time I taught this, 2 years ago, the students had managed to model (1) the behavior of binary inspiraling stars (of particular interest to us here, given the presence of Joel Weisberg on the faculty, as well as because Nelson Christensen’s group is part of the LIGO consortium) as well as (2) a sound wave in a solid, based on thinking of atoms as balls and springs strung together. And they’ve learned about momentum conservation, energy conservation, and all those things that you’re supposed to think about in intro mechanics. The kinds of forces we look at are significantly more general than the typical intro course, although it’s not supposed to be an ‘advanced’ course as much as an ‘alternate’ course. And I think it is an excellent alternative for reasons I have ranted about elsewhere — mainly that to only talk about falling balls and sliding blocks is a really silly way to introduce people to the power and breadth of Newtonian analysis.

I am currently focusing on the appropriate chunking and pacing of the material: I have 14 class meetings and 5 weekly lab meetings available to me, and the more I anticipate the rhythm of the term and the course, the less I shall have to adjust on the fly — there isn’t a lot of play with that sort of schedule.

Taking in a deep breath, to be let out at the end of the course …