Built on Facts

Disclaimer for casual readers: I write posts which vary wildly in technical difficulty, this one is a little more mathematical than most. Don’t let it scare you off! Even if you’re a little lost, it’s good to have seen it.
The various worked problems I’ve been doing recently have mostly been on the intro [...]

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I love teaching, but I have to say I am not a fan of teaching the summer session. Everything is way too disorganized. Oh well, at least it’s only for another three weeks or so.
The way undergraduate intro physics is taught is usually in two halves, and right now I’m teaching the second. [...]

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Yesterday in my recitation section I went through the chapter on electromagnetic induction, covering Faraday’s law and the displacement current term in Ampere’s law before assigning a quiz. Though this quiz really doesn’t need those concepts, it was a good opportunity to break out my all-time favorite Intro E&M quiz question.
Consider two parallel wires [...]

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I gave this quiz to my Physics 208 class this Monday, modified slightly from one of the textbook homework problems. I was going to work it out here, but I think I’ll leave the solution as a challenge for you.
A straight conducting wire of mass M and length L is placed on a frictionless [...]

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A couple days before I started teaching recitation sessions for Physics 208 (the E&M half of calc-based intro physics) this summer, I found out that in fact I was not teaching the second summer session, I’m teaching for the second half of the full summer session. Turns out there is a difference! For [...]

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Next semester I’m taking the graduate classical mechanics class, and so I’m trying to spend a little time this summer brushing up on my old undergraduate mechanics. It’s been about three years since I’ve had to do much of it, and I’ve dug out my old books and am working on some problems. [...]

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Vis consili expers mole ruit sua.
- Quintus Horatius Flaccus
The words of Horace above attain a spare and austere beauty in Latin, but the meaning is carried equally well in English. Force without wisdom falls of its own weight. Two different sets of words carry his millenia-old thoughts to the present time. There [...]

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When I was a young child, my uncle Fred used to try to convince me of some pretty outlandish things. His favorites were to say that the earth was flat and that England was a hoax. I was old enough to know better and I tried to argue as best I could, though [...]

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The brilliant folk-rock musician Jonathan Coulton has written a song about the Mandelbrot set. The set is a quite neat and famous mathematical object, and that it’s crossed over into immortalization in song is one of those beautifully weird things we are privileged to see in the internet age. No, it’s not really physics [...]

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In a vacuum, the speed of light is a universal constant: 299,792,458 m/s exactly. For light traveling through a substance like water or glass the speed is lower. The light hasn’t actually slowed down. Instead, the interaction with each successive atom in the material takes a little bit of time and so [...]

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