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

Interactions between the magnetic field and the gas remove angular momentum from the pair, allowing the two objects to spiral inward and form a binary system within a realistic timescale.

From Science Daily • Jun. 5, 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

The researchers showed that this motion can be passed directly to electrons, giving them orbital angular momentum without relying on traditional magnetic methods.

From Science Daily • Apr. 19, 2026

As the gravitational collapse continued, the primordial galaxies spun increasingly faster, because of the conservation of angular momentum.

From "Cosmos" by Carl Sagan