Chapter 11 Key Terms:

absolute angle	angular orientation of a body segment with respect to a fixed line of reference
angular acceleration	rate of change in angular velocity
angular displacement	change in angular position
angular velocity	rate of change in angular position
instant center	precisely located center of rotation at a joint at a given instant in time
radial acceleration	component of angular acceleration directed toward the center of curvature that indicates change in direction
radian	unit of angular measure used in angular-linear kinematic quantity conversions; equal to 57.3 degrees
radius of rotation	distance from the axis of rotation to a point of interest on a rotating body
relative angle	angle at a joint formed between the longitudinal axes of adjacent body segments
right hand rule	procedure for identifying the direction of an angular motion vector
tangential acceleration	component of angular acceleration directed along a tangent to the path of motion that indicates change in linear speed