# Angular Momentum

• The vector or cross product is another way to combine two vectors; it creates a vector perpendicular to both it the originals.
• The angular momentum of a body depends on the point chosen as the origin.
• The angular momentum of a body around a point is the cross product of the radius from the point to the body and the momentum of the body.
• Angular momentum is the rotational analog of linear momentum
• Just as the time derivative of linear momentum is force, the time derivative of angular momentum is torque.
• The angular momentum around a point of a body which moves directly towards that point is zero.
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Jack and Jill go to the carnival and ride the "Whirl-A-Kid."

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1:  What is the moment of inertia of Jack around the hub?

2:  What is the moment of inertia of Jill around the hub?

3:  What is the moment of inertia of one arm?

4:  What is the moment of inertia of both arms?

5:  What is the angular momentum of Jack?

6:  What is the angular momentum of Jill?

7:  What is the angular momentum of one arm?

8:  What is the angular momentum of both arms?

9:  What is the total angular momentum of Jack,
and Jill, and both arms of the Whirl-a-Kid?

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