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Homework Help: Ball in Horizontal Circle (Rotational Kinematics)

  1. May 31, 2009 #1
    1. The problem statement, all variables and given/known data

    A ball at the end of a string of length 0.75 m rotates at a constant speed in a horizontal circle. It make 3 rev/s.

    What is the period of the ball's motion?

    What is the ball's angular velocity?

    2. Relevant equations

    w = delta theta/delta t

    theta = 2*pi*r/r = 2*pi rad

    3. The attempt at a solution

    For period (in seconds):

    (3 rev/1s)*(2*pi rad/1 rev) = 6*pi rad/s

    (2*pi rad/1 rev)(1 s/6*pi rad) = 1/3 seconds

    I don't know where to go from here? Did I find the period in the correct manner?
  2. jcsd
  3. Jun 1, 2009 #2


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    Homework Helper

    Your period is OK.

    More simply it is 3 revs in 1 sec, so ...1 rev in 1/3 sec.
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