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Rotational Motion

  1. Jan 9, 2007 #1
    1. I need some ideas on how to demonstrate angular velocity and angular acceleration in the class.

    3. We have some wheels w/ handles on either side that we can use to show rotation. We're going to apply the equations of angular velocity and acceleration to that. Does anyone have any input on how we can prove to the class how these two concepts work and some ideas on how to apply a constant acceleration to the rotating wheel
  2. jcsd
  3. Jan 9, 2007 #2


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    The bicycle wheels can also be used to let people 'feel' angular momentum. Hold one handle and move the tire around. As long as the direction of the axis doesn't change, there's not much resistance. Try changing the direction of the axis, though. The greater the angular velocity, the greater the angular momentum.

    Applying constant angular acceleration to the tire's rotation will be a little tough, but showing the effects of constant acceleration on the tires motion is pretty easy since gravity will do the trick for you. If you suspend one end of the tire from a loop of rope, gravity will cause the tire to precess about the rope. If you think about the torque caused by one of the handles being supported by the rope and the other end being accelerated by gravity, you can detemine the direction of the torque vector using the right hand screw rule. Using right hand screw rule for the angular momentum vector, you have two vectors. Comparing them, you ought to be able to guess which direction the tire will rotate around the rope.

    Edit: Probably not quite what you're looking for since it doesn't deal directly with angular velocity and angular acceleration, but fun none the less.
    Last edited: Jan 9, 2007
  4. Jan 9, 2007 #3
    In order to get constant acceleration, you need to apply a constant force. A great example of this is a gyroscope. As you pull on the string that is wrapped around the axis (i.e. the force), the gyroscope wheel will accelerate.

    To show angular velocity, take the bike wheel and tape one of the spokes. Count every time the piece of tape passes a marked point for 10 seconds. You can then deduce, the wheel rotated "X" times in 10 seconds and the angular velocity is (X/10) rev / sec

    Hope this helps
    Last edited by a moderator: Jan 20, 2007
  5. Jan 9, 2007 #4
    Hey thanks guys. appreciate the help.
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