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Homework Help: Uniform Circular Motion.

  1. Jan 24, 2010 #1
    1. The problem statement, all variables and given/known data

    The speed of the tip of the minute hand on a
    town clock is 0.00182 m/s.
    What is the speed of the tip of the second
    hand of the same length?
    Answer in units of m/s.

    What is the centripetal acceleration of the tip
    of the second hand?
    Answer in units of m/s2.

    2. Relevant equations

    3. The attempt at a solution
    Ok to find the speed of the second, I multiplied by 60 and got .1092 m/s
    for the acceleration I'm not given r, so I need to find r using this equation, V=2pi r/T
    I was wondering what id T ? is it 60 seconds ? Thank you
    Last edited: Jan 24, 2010
  2. jcsd
  3. Jan 24, 2010 #2


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    V=2pi*r/T is just distance divided by time, so T has to be the time taken for the hand to make one revolution. Of course, that depends on which hand you're considering.
  4. Jan 24, 2010 #3


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    Gold Member

    You can find r by using the angular velocity ω from v = ω r. What is ω for the second hand?
  5. Jan 24, 2010 #4
    so I found r which is 1.638m and I used 60s for T
    I got .00728 for the acceleration and this isn't the right answer, please tell me what is it that I'm not doing right thanks.
  6. Jan 24, 2010 #5


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    If you don't show exactly how you got these numbers for the radius and for the acceleration, we cannot tell you what you are not doing right.
  7. Jan 24, 2010 #6
    I'm sorry, but it's ok I figured out what I was doing wrong.
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