# Advent

# Category archives for **Advent**

As the advent calendar moves into the E&M portion of the season, there are a number of possible ways to approach this. I could go with fairly specific formulae for various aspects, but that would take a while and might close out some other areas of physics. In the end, all of classical E&M comes…

Having covered most of what you need to know about classical physics, the traditional next step is to talk about electricity and magnetism, colloquially known as “E&M,” though really, “E and B” would be more appropriate, as the fundamental quantities discussed are the electric field (symbol: E) and the magnetic field (symbol: B), whose effect…

We kicked off our countdown to Newton’s birthday with his equations of motion, so it seems fitting to close out the section on classical mechanics with another of Newton’s equations, this time the Law of Universal Gravitation: Like all the other equations to this point, I’m cribbing this from the formula sheet for my just-completed…

Today’s advent calendar post was delayed by severe online retail issues last night and child care today, but I didn’t want to let the day pass completely without physics, so here’s the next equation in our countdown to Newton’s birthday: This is the final piece of the story of angular momentum, the undefined symbol from…

Now that we’ve defined angular momentum, the next equation on our countdown to Newton’s birthday tells us what to do with it: This is the Angular Momentum Principle, and as with energy and momentum before it, this relates the time derivative of the angular momentum (that is, how quickly it’s changing its value) to a…

Moving along through our countdown to Newton’s birthday, we come to the next important physical quantity, angular momentum. For some obscure reason, this gets the symbol L, and the angular momentum for a single particle about some point A is given by: This is probably the most deceptive equation we’ll see this season. Yesterday’s definition…

Following the basic pattern established at the start of our seasonal countdown to Newton’s birthday, today’s equation defines a piece that was left hanging in yesterday’s post: This is the technical definition of “work” in physics terms. It’s also probably the scariest-looking equation to this point, as it explicitly involves vector calculus– there’s an integral…

For the sixth day of our advent countdown to Newton’s birthday, we have the first equation that really departs from the usual notation. I’ve gotten to kind of like the way the Matter and Interactions curriculum handles this, though, so we’ll use their notation: This is what Chabay and Sherwood refer to as the Energy…

Moving along in our countdown to Newton’s birthday, we start to deal with equations that Sir Isaac never would’ve seen, because they deal with more abstract quantities than he worked with. The first and in some ways most important of these is energy: This is the full and correct expression for the energy of a…

Continuing our countdown to Newton’s birthday, let’s acknowledge the contributions of one of his contemporaries and rivals with today’s equation: This is, of course, Hooke’s Law for a spring, which he famously published in 1660: ceiiinosssttuv Clears everything right up, doesn’t it? OK, maybe not. This one’s not only in Latin, it’s a cryptogram, unscrambling…