1. Rotational motion (rotary motion/circular motion/radial motion) An object that rotates about an axis of rotation through an angle q, over a distance s

2. Rotational motion
Radian - an angle whose arc length is equal to its radius length
q = arc length
radius length units: m
q = s m/radian r
1 radian = 57.3˚
360˚ = 2pr
180˚ =

3. Rotational motion
Angular displacement - the change in the angle through which a point, line, or body is rotated about a specific axis, in a specific direction
Dq = change in arc length
distance from axis
Dq = Ds r