Angular momentum ($\vec{L}$) is a vector quantity defined as the product of an object's rotational inertia $I$ and its angular velocity $\vec{\omega}$:

The magnitude of angular momentum, $L$, depends on the rotational inertia and the angular speed:

$$L=I\omega$$

The magnitude of an object's angular momentum tells us how hard it is to stop its rotation.

Recall that $I$ depends on how mass is distributed relative to the rotation axis. Objects with mass farther from the axis have larger $I$. The angular velocity $\omega$ describes how fast the object spins.

From $L = I\omega$, angular momentum increases when either $I$ or $\omega$ increases.

Units of Angular Momentum

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