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How does rotation have vectors?

  1. Nov 15, 2015 #1
    In my textbook they used the right hand rule to show that rotation has vectors instead of just being positive or negative relative to its direction of rotation of a vinyl record. In the image the record was going clock wise so by the right hand rule it was going downward which makes sense, but are they also saying that if it was counter-clock wise then by the right hand rule it would have a vector in the upward direction? Does that mean it would move upward? I'm sorry if this sounds dumb, I just can't understand how we can apply vectors to rotation.
  2. jcsd
  3. Nov 15, 2015 #2
    There are a couple of inaccurately used words in your statement.
    1. "rotation has vectors". Rotation is a type of motion. It does not "have" vectors.
    2. "In the image the record was going clock wise so by the right hand rule it was going downward which makes sense". You said "it" was going downward. Ask yourself the question: What was going downward? Certainly not the vinyl record. It is NOT going downward. It is only going round and round.
    3. There is a si,i;ar statement about counter-clockwise rotation.
    The vector you are talking about does not give the direction of motion. Think of a tiny spot on your vinyl record. It is going round at the same rate as the record. At any instant, the spot is moving in a specific direction. That is the direction of the instantaneous velocity, and it is tangential to the circle in which the spot is moving.
    The vector that the right hand rule shows is the ANGULAR VELOCITY, or ANGULAR MOMENTUM. Nothing is actually moving in the direction of these vectors. Rather, something is rotating around these vectors. The direction of rotation and the direction of the vector are related by the right hand rule.
  4. Nov 15, 2015 #3
    Sorry for the complicated wording, I just wasn't sure how to word this question. Thanks for clearing it up though, it makes sense now, thanks!
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