Moment of inertia

The angular momentum of the figure skater is conserved—as she decreases her radius by retracting 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 a body's resistance to angular acceleration or deceleration, equal to the product of the mass and the square of its radius measured perpendicularly to the axis of rotation.

Moments of inertia for a few objects

The moment of inertia I = ∫r²dm of 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 Template:Webarchive
• A table of moments of inertia Template:Webarchive
• Parallels between rotation and translation HyperPhysics

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