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Introduction to Angular KinematicsWhat’s more fun than moving in a straight line? Moving on a plane. What’s more fun than that? Moving in space. What’s better than that?
They weren’t sure, so the Official Academy of Physicists, which does not actually exist, concocted moving in a circle, or angular motion. We touched on that in the article on uniform circular motion, where I gave the expression most fundamental to the study of angular motion:
Every equation we use in studying angular motion either has a direct analogue in linear motion or is a variant on that equation. For example, you’ll surely remember the equation for torque:
Therefore, here’s a quick rundown of important angular quantities for a distance
Two quick notes — first, about units: we measure angles in radians The second note regards the nature of angular velocity, acceleration, momentum, et cetera: since they are created by the cross product, it’s worth mentioning that these are not in fact true vectors but rather pseudovectors; that is, if we apply an improper rotation to them, they flip sign. This shouldn’t affect your calculations for the most part, but I think it merits mention. Now that we’ve established the angular analogues of most quantities involved in rotation, we have one more to discuss—and a very important one it is—that of rotational inertia (also called moment of inertia). But it’s a somewhat involved topic, so we’ll save that one for next time. |