Stewart, College Physics for the AP® Physics 1 & 2 Courses, 3E, Chapter 10

angular acceleration

The rate at which the angular velocity is changing with respect to time.

angular displacement

The angle through which an object or a point on a rotating extended object moves on a circular path in a given time interval.

angular position

The angle of a line to the point of interest on an extended object, measured from a reference axis.

angular speed

How fast the angular position is changing with respect to time. As long as a system does not change its direction of rotation, angular speed is the magnitude of the angular velocity.

angular velocity

The angular displacement of a point on a rotating extended object divided by the time interval for the point to undergo that displacement. A vector quantity, its direction is determined by a right-hand rule.

cross product (vector product)

The product of two vectors in three dimensions that is itself a vector at right angles to both the original vectors, with a direction given by the right-hand rule and a magnitude equal to the product of the magnitudes of the original vectors and the sine of the angle between their directions.

extended free-body diagram (force diagram)

A free-body diagram modified to show where on an extended object—with respect to the rotational axis—the forces are exerted. This type of diagram aids in the calculation of torque in cases where there is rotational motion.

extended object

A system made up of connected objects that may change position with respect to one another when the system moves.

force diagram (extended free-body diagram)

A free-body diagram modified to show where on an extended object—with respect to the rotational axis—the forces are exerted. This type of diagram aids in the calculation of torque in cases where there is rotational motion.

lever arm

The perpendicular distance from the rotation axis to the line of action of a force exerted on an extended object.

line of action

An extension of the force vector F through the point where the force is exerted on an extended object.

parallel-axis theorem

Expression determining the rotational inertia of a rigid body about a given axis in terms of the rotational inertia about a parallel axis running through its center of mass and the distance between the two axes.

right-hand rule

A rule that uses the right hand to determine the orientation of vector quantities normal to a plane; for example, used to find the direction of the angular momentum vector around an axis of rotation.

rigid body

An extended object whose shape doesn’t change as it rotates.

rotation

Motion in which an extended object rotates about an axis.

rotational equilibrium

A state of zero angular acceleration, resulting from a rigid body on which no net torques are exerted.

rotational inertia

A property of a body that defines its resistance to a change in angular velocity about an axis of rotation.

rotational kinematics

The study of rotational motion, including angular velocities and angular acceleration, without reference to the causes of that motion.

rotational kinetic energy

Kinetic energy associated with the rotation of a system around an axis.

torque

The tendency of a force to rotate an extended object.

translation

Motion in which the center of mass of a system moves from one point in space to another.