### Angular Momentum

The*angular momentum*of a mass rotating in a circle of radius with angular velocity (rad/s), is defined by

*mass moment of inertia*of the rigid body (§B.4.4).

#### Relation of Angular to Linear Momentum

Recall (§B.3) that the momentum of a mass traveling with velocity in a straight line is given by*tangential speed*of the mass along the circle of radius is given by

Thus, the angular momentum is times the linear momentum . Linear momentum can be viewed as a renormalized special case of angular momentum in which the radius of rotation goes to infinity.

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