Sections

Glossary
# Glossary

- angular acceleration
- the rate of change of angular velocity with time

- angular momentum
- the product of moment of inertia and angular velocity

- change in angular velocity
- the difference between final and initial values of angular velocity

- kinematics of rotational motion
- describes the relationships among rotation angle, angular velocity, angular acceleration, and time

- law of conservation of angular momentum
- angular momentum is conserved, i.e., the initial angular momentum is equal to the final angular momentum when no external torque is applied to the system

- moment of inertia
- mass times the square of perpendicular distance from the rotation axis; for a point mass, it is $I={\text{mr}}^{2}$ and, because any object can be built up from a collection of point masses, this relationship is the basis for all other moments of inertia

- right-hand rule
- direction of angular velocity ω and angular momentum L in which the thumb of your right hand points when you curl your fingers in the direction of the disk's rotation

- rotational inertia
- resistance to change of rotation; the more rotational inertia an object has, the harder it is to rotate

- rotational kinetic energy
- the kinetic energy due to the rotation of an object. This is part of its total kinetic energy

- tangential acceleration
- the acceleration in a direction tangent to the circle at the point of interest in circular motion

- torque
- the turning effectiveness of a force

- work-energy theorem
- if one or more external forces act upon a rigid object, causing its kinetic energy to change from ${\text{KE}}_{\text{1}}$ to ${\text{KE}}_{\text{2}}$, then the work $W$ done by the net force is equal to the change in kinetic energy