The Angular Impulse-Momentum Theorem states that the net angular impulse acting on an object is equal to the object's change in angular momentum.

Using the definition of angular impulse we can express this in terms of change in angular momentum, average torque, and time.

The interactions are vector quantities. The impulse vector accounts exactly for the difference between the final and initial angular momentum vectors. Notice the change in angular momentum is in the same direction as torque.

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