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Quick question about centrifuge?

  1. May 20, 2010 #1
    Hello everyone,

    If some test tubes are placed in a centrifuge to separate the liquid in them, does the separation occur after the spinning is finished. I can't see how the centrifugal force can act when the tubes are spinning, does it act after it finishes. Thanks
     
  2. jcsd
  3. May 20, 2010 #2

    russ_watters

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    Staff: Mentor

  4. May 20, 2010 #3
    Thanks for the reply Russ!!

    Ok then I haven't understood this concept.

    centrifugal.free.gif

    Ok a person was initially travelling at V direction and then centriptal force acted upon him to make him go in a circle. Now if centrifugal force is inertia, why is acting opposite to centripetal force, shouldn't it act tangent to the circle, if I stop the centripetal force the man would travel tangent to the circle. If inertia is in that direction why is centifugal force acting some other way, also I read that this force really doesn't exist, then how does it separate the liquid. Thanks!!

    Edit: Ok I think I worked it out. If there is a box in the back seat of the car, and the car is travelling straight and suddenly acted upon by the centripetal force, the box would obviously try to keep moving forward with cars orginal speed, but the centripetal force has already turned the car, so the box is not going to hit the front seat but the side of the car.
     
    Last edited: May 20, 2010
  5. May 20, 2010 #4
    From the test tube's perspective, there is no centripetal force, but there is centrifugal force. Its the opposite for an observer watching the test tube. Careful not to mix these cases up.
     
  6. May 20, 2010 #5
    How does the test tube only observe centrifugal force? The force on the test tube is the centripetal force acting inward.
     
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