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 $I = {mr}^{2}$ 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 ${KE}_{1}$ to ${KE}_{2}$ , then the work $W$ done by the net force is equal to the change in kinetic energy