Today is the first day of the last week of class, hallelujah. Unfortunately, it’s also the first class on rotational motion and angular momentum. This is unfortunate because it’s the hardest material in the course– angular momentum doesn’t behave in as intuitive a manner as linear momentum, and the math involved is the most complicated of anything we do in the course.
This mostly has to do with the vector product, or “cross product.” Angular momentum can be written as the product between the position vector from the axis of rotation to the moving object and the linear momentum of the moving object. The resulting vector is at right angles to both of the original vectors.
This is just plain weird, but it leads to most of the interesting properties of angular momentum. Unfortunately, it also requires a good deal of careful attention to detail to get it right. And we’ve got two classes in which to discuss it, two classes that fall in the first week of June, when everybody’s brains are completely shot (faculty included), and all thoughts are on the imminent summer.
It’s a shame, because this is the coolest material in intro mechanics. But it’s almost impossible to do it justice in these conditions. As a result, I end up kind of dreading the whole thing.
Stupid academic calendar.