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.

• Viewgraph 1

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  • A review of the cross product, if you need it

• Viewgraph 6

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  Jack and Jill go to the carnival and ride the "Whirl-A-Kid."

  

  
      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?
  
     

• Viewgraph 9

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• Viewgraph 11

• Viewgraph 12

• Viewgraph 13

• Viewgraph 14