angular velocity

— 1963, Richard Feynman, The Feynman Lectures on Physics (1963) Ch. 18 Rotation in Two Dimensions, 18–2 Rotation of a rigid body. First, we have the angle θ which defines how far the body has gone around; this replaces the distance s, which defines how far it has gone along. In the same manner, we have a velocity of turning, ω=dθ/dt, which tells us how much the angle changes in a second, just as v=ds/dt describes how fast a thing moves, or how far it moves in a second. If the angle is measured in radians, then the angular velocity ω will be so and so many radians per second. The greater the angular velocity, the faster the object is turning, the faster the angle changes.