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A spinning cap that reverses direction?

  1. Apr 26, 2008 #1
    I was watching a video on where this guy spins a a dial or capsule or a cap (I couldn't really tell, but it was like a long thing cylinder capsule look a like) and well he gave it a quick push and the cap came to a stop and than reverses direction.

    What could cause this?

    I know that angular momentum is not conserved because of external torque (gravity) and friction causes the thing to come to a halt, but why would it reverse direction. Where does it get the force to reverse direction?
  2. jcsd
  3. Apr 26, 2008 #2

    Doc Al

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    Staff: Mentor

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