Angular momentum
Definition
Angular momentum is the rotational analog of linear momentum, representing the quantity of rotation of an object. It is a vector quantity given by the product of an object's moment of inertia and its angular velocity.
5 Must Know Facts For Your Next Test
- Angular momentum ($\mathbf{L}$) is calculated as $\mathbf{L} = I \mathbf{\omega}$, where $I$ is the moment of inertia and $\mathbf{\omega}$ is the angular velocity.
- In a closed system with no external torques, angular momentum is conserved.
- The SI unit for angular momentum is kilogram meter squared per second (kg⋅m²/s).
- The direction of angular momentum follows the right-hand rule: curl your fingers in the direction of rotation, and your thumb points in the direction of $\mathbf{L}$.
- Torque ($\tau$) causes changes in angular momentum and is related by $\tau = \frac{d\mathbf{L}}{dt}$.
Review Questions
- How do you calculate angular momentum for a rotating object?
- What happens to the angular momentum in a system with no external torques?
- Which rule helps determine the direction of angular momentum?
"Angular momentum" appears in:
Subjects (4)
Related terms
Moment of Inertia: A measure of an object's resistance to changes in its rotation rate, dependent on mass distribution relative to the axis.
Torque: A force that causes an object to rotate about an axis; it can change an object's angular momentum.
Conservation of Angular Momentum: $\text{A principle stating that if no external torque acts on a system, its total angular momentum remains constant.}$
