Back to 'Unit 8: Momentum and Collisions'

Topic outline

  • 8.5: Conservation of Angular Momentum

    Collapse all Expand all

    We define angular momentum as L=I\omega . It is similar to the momentum defined for linear motion. As such, angular momentum in a system is conserved in the same way that linear momentum is conserved. Therefore, we can say that L=L' , where L is the initial angular momentum in a system and L' is the final angular momentum in the system. We can also write this as:

    I\omega=I'\omega'  

    We see conservation of angular momentum in many everyday examples. As you read, pay attention to the example of the spinning figure skater in Figure 10.23. In the first picture, the figure skater is spinning with her arms out on a frictionless ice surface. In the second picture, she pulls her arms in, and her rotational velocity increases. When the figure skater pulls in her arms, she lowers her moment of inertia. Because angular momentum is conserved, because her moment of inertia decreases, her angular velocity must therefore increase.