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Homework Help: Centripetal Force acceleration

  1. Jan 27, 2009 #1
    1. A computer is reading data from a rotating CD-ROM. At a point that is 0.0330 m from the center of the disk, the centripetal acceleration is 264 m/s2. What is the centripetal acceleration at a point that is 0.0702 m from the center of the disc?

    2. ac=v2/r

    3. So my thoughts here are that it should be assumed that the velocity is constant. So I need to fine that velocity for the known radius and acceleration with the equation about. After I find the velocity, I can plug it into the equation with the new radius and find the acceleration that way.
    v2=8.712 m/s
    v=2.95161 m/s

    then plugging that into the equation with the other radius
    ac=124.10256 m/s2

    This is not the right answer for my homework though. Not sure what I am doing wrong. Anyone know?
  2. jcsd
  3. Jan 27, 2009 #2
    well...the disc is rotating...so v is NOT constant. However, for constant rotation, angular velocity is constant. Use the relation between that and v, and modify your equation for acceleration.
  4. Jan 27, 2009 #3
    ok, I understand now that the velocity is not constant. I don't believe we have covered angular velocity yet in class, unless I am just overlooking it. How do you do that? I did set up a proportion though with the velocity and radius and got it correct.
  5. Jan 27, 2009 #4


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