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A Wheel Motion Problem

  1. Dec 17, 2013 #1
    Which statement concerning a wheel undergoing rolling motion is true
    (a) The angular acceleration of the wheel must be zero m/s2.
    (b) The tangential velocity is the same for all points on the wheel.
    (c) The linear velocity for all points on the rim of the wheel is non-zero.
    (d) The tangential velocity is the same for all points on the rim of the wheel.
    (e) There is no slipping at the point where the wheel touches the surface on which it is rolling

    this is my attempt

    a) IDK = I don't know cause I don't know if this wheel is at a constant velocity, should I assume this wheel is going at a constant velocity?
    b) IDK = I don't know cause I don't know if this wheel is at a constant velocity, should I assume this wheel is going at a constant velocity?
    c) NO = linear velocity should be at some number at each point
    d) YES = I think the tangential velocity is the same assuming this wheel is at constant velocity
    e) No - there has to be slipping right? common sense RIGHT?

    I guess I first need to know if this wheel is going at a constant velocity, am i totally out there?
     
  2. jcsd
  3. Dec 17, 2013 #2

    berkeman

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    Your answer is correct. They on purpose didn't say if it was accelerating or slipping, so that eliminates some of the choices. The others are just false, even for non-accelerating rolling motion.
     
  4. Dec 17, 2013 #3

    haruspex

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    Answering IDK to (a) is wrong. The statement is that it "must be zero". If there is any situation in which it is not zero then the statement is false.
    For (b), your reason for saying IDK is wrong. The question refers to velocity at some instant. This will not be affected by whether it is accelerating. (I'm not saying, at this point, whether the statement is true, false, or indeterminate.)
    Similarly, I don't understand your reasoning in (c). In fact, the reason you offer suggests you would answer True.
    Again, in (d), the answer is not dependent on velocity being constant.
    For (e), it does say rolling motion. Rolling is rolling, i.e. NOT slipping, by definition. Why do you think it must be slipping?
     
  5. Dec 17, 2013 #4

    berkeman

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    Thanks for the clarifications haruspex! I only meant that his answer to d) was correct.
     
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