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Homework Help: Centripetal Forces Help please

  1. Jan 7, 2010 #1
    1. The problem statement, all variables and given/known data
    How much force is needed to swing a 4kg mass in a 3m radius horizontal circle so that each cycle takes exactly 2 seconds. Answer is 118N but the problem is how do I get to that...


    2. Relevant equations
    V=2Pir/T F=mv^2/r


    3. The attempt at a solution
    I tried using F=mv^/r one but I got nowhere close my teacher just solves problems without explaining at all and I have no clue how to solve it except find numbers.


    Thank you for your time.
     
  2. jcsd
  3. Jan 7, 2010 #2

    rock.freak667

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    I one cycle takes 2 seconds, how many cycles are in one second? Hence what is the angular velocity of the bat?
     
  4. Jan 7, 2010 #3
    It doesn't say thats all the info that the problem gives me.
     
  5. Jan 7, 2010 #4

    rock.freak667

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    I am quite sure you can find the the number of cycles in 1 second given, that 1 cycle takes 2 seconds.
     
  6. Jan 7, 2010 #5
    Aren't I looking for the force of the swing?
     
    Last edited: Jan 7, 2010
  7. Jan 7, 2010 #6

    rock.freak667

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    Yes but you need to get the periodic time to get F.
     
  8. Jan 7, 2010 #7
    Oh I get it now thank you so much.
     
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