Does Centrifugal Force Act During or After Spinning in a Centrifuge?

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In summary, The conversation discusses the concept of centripetal and centrifugal forces and how they act in a centrifuge. It is explained that the forces act while the centrifuge is running, not after, and that the centrifugal force is not a real force but rather a result of inertia. The example of a car turning is used to demonstrate how these forces act differently from different perspectives. The test tube only observes centrifugal force while the observer sees the centripetal force acting inward.
  • #1
sameeralord
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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
 
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  • #3
russ_watters said:
It acts while the centrifuge is running, not after. http://en.wikipedia.org/wiki/Centripetal_force

Thanks for the reply Russ!

Ok then I haven't understood this concept.

centrifugal.free.gif


Ok a person was initially traveling 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 traveling 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.
 
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  • #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.
 
  • #5
Academic said:
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.

How does the test tube only observe centrifugal force? The force on the test tube is the centripetal force acting inward.
 

1. How does a centrifuge work?

A centrifuge works by spinning samples at high speeds, creating a centrifugal force that separates the components based on their density. The heavier components move to the bottom of the tube while the lighter components stay towards the top.

2. What is the purpose of using a centrifuge in the laboratory?

The main purpose of a centrifuge is to separate components of a mixture, such as cells or proteins, based on their density. It is also commonly used to concentrate samples and purify substances.

3. How do I choose the right speed and time for my centrifugation process?

The speed and time for centrifugation will depend on the type of sample and the components you are trying to separate. It is important to consult the manufacturer's instructions and any relevant protocols to determine the appropriate settings for your specific experiment.

4. Can I use a centrifuge for all types of samples?

No, there are different types of centrifuges designed for specific samples and purposes. For example, microcentrifuges are used for small volumes and high speeds, while ultracentrifuges are used for larger volumes and lower speeds. It is important to use the correct type of centrifuge for your sample to ensure accurate results.

5. How do I maintain and clean a centrifuge?

Regular maintenance and cleaning of a centrifuge are important for its proper functioning and to prevent contamination. It is recommended to clean the rotor and centrifuge chamber after each use and to regularly check and replace any worn or damaged parts. It is also important to follow the manufacturer's instructions for proper maintenance procedures.

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