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Homework Help: Direction of angular velocity

  1. Nov 16, 2009 #1
    1. The problem statement, all variables and given/known data
    A CD player spins a disc in a clockwise direction when looking at the player from the top. What is the direction of the angular velocity.

    2. Relevant equations

    3. The attempt at a solution
    OK, the key for this practice exam says the answer is in the -y direction. I used the right hand rule to see that the direction is negative, but I thought it would be in the -z direction. Can someone explain why it is -y?
  2. jcsd
  3. Nov 16, 2009 #2
    I believe they have made the answer this way as you are only using two dimensions. If you take the vertical y-axis as the axle for the rotation, your right thumb will be pointing in the negative y-direction when you use the right hand rule.
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