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Period of precession

  1. Apr 24, 2015 #1
    1. The problem statement, all variables and given/known data
    upload_2015-4-23_23-12-37.png

    2. Relevant equations
    upload_2015-4-23_23-13-22.png
    this was a formula I just found on Wikipedia, but it seemed to be right for this problem.

    3. The attempt at a solution

    so we have the diameter of the of the wheel = 0.7 m

    mass of wheel = 0.25 kg

    distance of the rod attached = 0.2m

    angular velocity of wheel converted to radians = 27 rad/s

    moment of inertia for wheel = m r2

    Ts = is the period of of the wheel

    Tp is what we are solving for.



    which comes out to be 639.7 seconds. if my math is correct. but this answer seems extremely unlikely

    so the wheel moves to the left, but how can I figure out the speed at which it moves at?
     
    Last edited: Apr 24, 2015
  2. jcsd
  3. Apr 24, 2015 #2

    haruspex

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    What are you substituting for r in the Wiki formula? What do you have for Ts?
     
  4. Apr 24, 2015 #3
    r should be the length of the rod, which is 0.2m.

    and Ts is 1/258 = 0.00387 seconds per revolution.

    correct?
     
  5. Apr 24, 2015 #4

    haruspex

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    The wheel's rotation rate is given as 258 revolutions per what?
     
  6. Apr 24, 2015 #5
    minutes, oh no! i forgot to convert
     
  7. Apr 24, 2015 #6
    new answer comes out to be 10.7 seconds, which is sounds reasonable
     
  8. Apr 24, 2015 #7

    haruspex

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    Yes, it does.
     
  9. Apr 24, 2015 #8
    ok, lets say i had no access to the internet, and I had no way of finding that formula, how would I then find the speed at which the wheel moves to the left?
     
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