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

Although orbital angular momentum entanglement has been widely explored, it has often been considered fragile.

From Science Daily • Mar. 21, 2026

These filaments also act as pathways that funnel matter and angular momentum into galaxies.

From Science Daily • Dec. 25, 2025

For stars moving in a galaxy's gravitational field, both energy and angular momentum are conserved: they remain the same over time.

From Science Daily • Mar. 21, 2024

"The research was conducted by employing helical light beams carrying orbital angular momentum to probe the optical properties of amorphous and crystalline materials," explains Professor Bhardwaj.

From Science Daily • Feb. 29, 2024

Conservation of angular momentum is your best friend.

From "Legendary Frybread Drive-In" by Cynthia Leitich Smith