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Homework Help: Question about the sign of angular velocity

  1. May 3, 2013 #1
    1. The problem statement, all variables and given/known data
    The problem is here: It is question #4,
    http://faculty.mint.ua.edu/~pleclair/ph125/Exams/Ex3/ph125_s09_exam3.pdf [Broken]

    2. Relevant equations
    See Below

    3. The attempt at a solution
    I have already gotten the answer and know it is correct:
    where m is the mass of the clay
    My teacher says that the answer I have written above should have a negative sign in front of it. However, I thought angular speed was defined as the magnitude of angular velocity, meaning it is always positive. Who is correct here?
    Last edited by a moderator: May 6, 2017
  2. jcsd
  3. May 3, 2013 #2


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    Homework Helper

    You are right, the angular speed was asked, and it is the magnitude of the angular velocity, positive.
    The angular velocity itself is negative.

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