Quick question about centrifuge?

[scilearner]

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

[swansont]

It only acts while the centrifuge is spinning. That's the only time there is a centripetal/centrifugal force.

[scilearner]

It only acts while the centrifuge is spinning. That's the only time there is a centripetal/centrifugal force.

 

Thanks swansoft for the reply Ok then I haven't understood this concept.

 

 

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!!

Edited May 20, 2010 by scilearner

[swansont]

The centrifugal force is not simply inertia.

 

It is a force the ball feels in its own frame, when trying to make it look like it's in an inertial frame; in this regard it's a fictitious force pushing out, because it's pretending the circular path is straight.

 

In another view, it's the force the ball exerts on the rope, but the motion is dictated by the forces on an object, not by the forces they exert. In that regard, the centripetal force and centrifugal force are paired by Newton's 3rd law.

 

In a centrifuge, the real force is centripetal (we don't call it a Centripete, but I think that might catch on), and it will be exerted by the test tube on the liquid, and through the liquid as pressure.

[scilearner]

The centrifugal force is not simply inertia.

 

It is a force the ball feels in its own frame, when trying to make it look like it's in an inertial frame; in this regard it's a fictitious force pushing out, because it's pretending the circular path is straight.

 

In another view, it's the force the ball exerts on the rope, but the motion is dictated by the forces on an object, not by the forces they exert. In that regard, the centripetal force and centrifugal force are paired by Newton's 3rd law.

 

In a centrifuge, the real force is centripetal (we don't call it a Centripete, but I think that might catch on), and it will be exerted by the test tube on the liquid, and through the liquid as pressure.

 

Thanks again After reading your reply and thinking I think I understood it.

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.