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Homework Help: Rate of roation of a wheel

  1. Feb 23, 2010 #1
    1. The problem statement, all variables and given/known data

    Basically the problem is asking me to find the rate of rotation of a space station that is in the shape of a wheel 120m in diameter, and rotates to provide an "artificial gravity" of 3.00 m/s.

    And it has to be in rev/min.

    2. Relevant equations

    The only equation so far I that has to deal with this is the one

    ac = [tex]v^2/r[/tex]

    3. The attempt at a solution

    it seemed pretty simple and straightforward. So first i took the gravity which is of course the acceleration in this case. And then set it equal to v^2/60.

    Then i solved for v.

    After solving for v I used that to see how long one revolution is by using the equation, v=d/t. Substituting in the 120 m for d.

    So I send up with a time in sec for every 120m revolution.
    Then I converted from sec to min by divinding by 60.

    I still can't get the answer in the book.
  2. jcsd
  3. Feb 23, 2010 #2


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    Homework Helper

    Hi Ninjaku! :smile:

    (have an omega: ω and a pi: π and try using the X2 tag just above the Reply box :wink:)
    Did you use the 2π factor to convert radius to circumference? :wink:

    (and btw it would have been easier to start with the alternative formula ac = ω2r instead of v2/r)
  4. Feb 23, 2010 #3
    Hey thanks for the reply.

    I retried the the computation with the 2π conversion factor that I forgot on my first try. And my answer is a little closer but still no cigar.

    The answer in the book is 2.14rev/min

    I got .084388.

    Oh and I'm not reallly familiar with that other formula, what does omega represent in that equation.
  5. Feb 23, 2010 #4


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    Well, I make it 2.14 also.

    Show us how you got .084388.

    (ω is the angular velocity in radians per second: v = ωr, ω = v/r :wink:)
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