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Very Simple Angular Physics Problem

  1. Nov 15, 2006 #1
    Hi there, brand new to the site. Came across it when googling for help on tangential velocity in a rotational problem.
    Anyhow I have an online homework due at midnight and would love to have any help possible with this question before then.

    Heres the problem....
    The hour hand on a certain clock is 8.9 cm long. Find the tangential speed of the tip of this hand in µm/s.

    I tried v= w(angular velocity)r
    so v= 2pi*r/ (60)(60) and got 155.3µm/s

    This however is incorrect and any help to lead me the right way is greatly appreciated :D

    Im an A student in Physics but just dont grasp rotation as well as the other topics.
    This question is probably very simple but it is just not clicking for me, maybe I am missing the correct formula to use?
     
  2. jcsd
  3. Nov 15, 2006 #2
    How long does it take the hour hand of a clock to make one complete revolution?
     
  4. Nov 15, 2006 #3
    3600 sec which is why i divided by that...is that not correct?:confused:
     
  5. Nov 15, 2006 #4
    One hour is equal to 3600 s. This is not the total time it takes the hour hand to make one complete revolution, however.
     
  6. Nov 15, 2006 #5
    oh damn so i should multiplying 3600 * 24 then too!

    see i knew i was making a dumb mistake, thanks alot!! :D
     
  7. Nov 15, 2006 #6
    There are 24 hours in a day. But, when the hour hand of a clock goes around once, how many hours has it gone through?
     
  8. Nov 15, 2006 #7
    ahhh 12, tricky, tricky
     
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