angular momentum

American  

noun

Physics.

1. the product of the moment of inertia of a body about an axis and its angular velocity with respect to the same axis.

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angular momentum British  

noun

1. a property of a mass or system of masses turning about some fixed point; it is conserved in the absence of the action of external forces

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angular momentum Scientific  

/ ăng′gyə-lər /

1. A measure of the momentum of a body in rotational motion. The angular momentum of rigid bodies is conserved; thus, a spinning sphere will continue to spin unless acted on by an outside force. Changes in angular momentum are equivalent to torque. In classical mechanics, angular momentum is equal to the product of the angular velocity of the body and its moment of inertia around the axis of rotation. It is a vector quantity; the vector points up along the axis of counterclockwise rotation. In quantum mechanics, the angular momentum of a physical system is quantized and can only take on discrete values.

2. See also Planck's constant spin

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Etymology

Origin of angular momentum

First recorded in 1865–70

Example Sentences

The team studied how angular momentum travels between lattice vibrations, which are coordinated motions of atoms inside a crystal.

From Science Daily • May 24, 2026

Although Umklapp processes are already known in other areas of condensed matter physics, this is the first experimental demonstration involving lattice angular momentum.

From Science Daily • May 24, 2026

According to the researchers, the result acts as a direct quantum mechanical signature of angular momentum conservation inside solids.

From Science Daily • May 24, 2026

For the first time, researchers demonstrated that chiral phonons can directly transfer orbital angular momentum to electrons in a non-magnetic material.

From Science Daily • Apr. 19, 2026

Neutrinos, like protons, electrons and neutrons, carry an intrinsic angular momentum, or spin, while photons have no spin at all.

From "Cosmos" by Carl Sagan