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Homework Help: Centrifuge Problem (Circular Motion)

  1. Jan 20, 2014 #1
    1. The problem statement, all variables and given/known data

    A Centrifuge rotates at 12000rpm. What is this in radians per second?

    If the radius of this centrifuge is 150mm, what is the centripetal acceleration?

    2. Relevant equations

    v2 / r

    v = rω

    a = rω2

    3. The attempt at a solution

    First I converted the 12000rpm to 1256.64 rad/sec.

    12000 / 60 = 200 Rev. per minute.

    200 x 2∏ = 1256. 64 rad/sec

    Onto the centripetal acceleration, I was given a = rω2

    a = 0.15 x 1256.642

    a= 236871.61 m/s2

    I'm just a little thrown off by how incredibly large the number is and I don't really have any idea of how a centrifuge usually moves. Any help?

    Would be much appreciated.
  2. jcsd
  3. Jan 20, 2014 #2


    User Avatar

    Staff: Mentor

    Welcome to the PF.

    I only see one problem in your work, and it's just a simple typo that doesn't change the numbers. See where I fixed it in the quoted text above.

    And yes, the acceleration does seem high, but after all that's what centrifuges are for. I used Google to look up some typical specs on labratory-grade centrifuges to see if the acceleration number you calculated is reasonable. The 12,000 rpm given number is pretty fast for the centrifuges that I looked up, but the size is in the typical range.

    Convert your acceleration into the number of g's (g = 9.8m/s^2), and compare your answer to what you find on Google. Post what you find so we can see what you are getting...
  4. Jan 20, 2014 #3


    User Avatar
    2017 Award

    Staff: Mentor

    That acceleration value is fine for a centrifuge. And it is still far away from their limits.
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