Moment of inertia

The angular momentum of the ice skater is conserved—as she retracts her arms and legs, her moment of inertia decreases, but her angular velocity increases to compensate.

Moment of inertia ($I$), also called "angular mass" (kg·m²), is the inertia of a rotating body with respect to its rotation.

It is a rotating body's resistance to angular acceleration or deceleration, equal to the product of the mass and the square of its perpendicular distance from the axis of rotation.

Moments of inertia for a few objects

The moment of inertiaI=∫r²dm for a hoop, disk, cylinder, box, plate, rod, and spherical shell or solid can be found from this figure.

Related pages

• Angular momentum
• Torque

Other websites

• Angular momentum and rigid-body rotation in two and three dimensions
• A table of moments of inertia
• Parallels between rotation and translation HyperPhysics