1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook