Angular Momentum and Fixed Axis Rotation
Ok so, we’ve talked about linear motion and circular motion, but we haven’t talked about rotational motion yet! Well, a whole lot of things rotate, so the next couple of chapters will be dedicated to analyzing rotational motion.
We’ll find that many of the concepts analyzed in previous chapters have counterparts in rotational motion. For example, just as there’s a linear momentum, there’s an angular momentum as well. So many of the equations that we learned before will look familiar, but with force swapped out with torque, mass swapped out with inertia, etc. In fact, here’s a table of all of these objects and the counterparts:
| linear motion | rotational motion |
|---|---|
| (mass) | (rotational inertia) |
| (position) | (angle) |
| (velocity) | (angular velocity) |
| (acceleration) | (angular acceleration) |
| (linear momentum) | (angular momentum) |
| (force) | (torque) |
I want to emphasize these similarities because it will help build some intuition for rotational motion, though I should be careful not to equate rotational and linear motion. Because while there are many similarities, there are still differences.
All right, let’s start rolling!