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Homework Help: Acceleration and rotation of centrifuge

  1. Oct 7, 2007 #1
    1. The problem statement, all variables and given/known data

    A typical laboratory centrifuge rotates at 4200 rpm. Test tubes have to be placed into a centrifuge very carefully because of the very large accelerators. a.) What is the acceleration at the end of a test tube that is 11 cm from the axis of rotation? b.) For comparison, what is the magnitude of the acceleration a test tube would experience if dropped from a height of .8 m and stopped in a 1.0 ms long encounter with a hard floor?

    2. Relevant equations

    w=2pi radians (f)
    a = w^2 r

    3. The attempt at a solution

    I tried finding the frequency, then using the frequency to find w, which I got to be 439.823. Then I tried finding a, which I got to be 48.381.
  2. jcsd
  3. Oct 7, 2007 #2


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    you forgot to square the w term!
  4. Oct 8, 2007 #3
    use T= 2(pi)(r)/v to get the velocity and then use a= v^2/r to get part a
  5. Oct 8, 2007 #4


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    And be sure to include your units.
  6. Oct 8, 2007 #5
    I did forget to square the w term. I got 21278.87m/s^2 for part a.
  7. Oct 8, 2007 #6
    For part b, I thought to just use Yf = Yi + Viy(t) + 1/2 (a) (t^2). I got 1.6E6 m/s^2, but it said it was wrong.
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