Angular velocity is often misstated

摘要

Ask any engineer what the velocity of a point on a rigid body is, and he will correctly say that it is the time rate of change of a linear position vector. Ask any engineer what angular velocity is, and he most likely will incorrectly say that it is the time rate of change of an angular position vector. In both cases, there is usually no mention of the reference frames involved. The misunderstanding of angular velocity—and the ambiguity that imprecise notation creates—can lead to errors that cause lost time and money, and even tragic results.