Separation of Fluids in a Centrifuge

[Lukeblackhill]

Morning Mates,

I have a question based in a statement take from Berkeley Physics Course, Vol.1 - Mechanics, pg. 102-103, where it reads,

"Suspended molecules whose density (mass/volume) is different from that of the surrounding liquid will experience in the ultracentrifuge cell a strong force tending to separate them from the fluid. If their density is the same as the liquid, there is no separation effect. If their density is less than that of the liquid, the differential force is inward".

My question is quite simple actually: when two or more fluids are together, why denser fluids go to the edge and less dense fluids go to the middle?

P.S. From the things I read, I think it is because considering m=d.v, denser fluids will experience bigger centrifugal forces, if we consider the relation F=m(w²r).

Thank you!
Cheers,
Luke.

 

[A.T.]

My question is quite simple actually: when two or more fluids are together, why denser fluids go to the edge and less dense fluids go to the middle?

For the same reason denser parts sink to the bottom in a gravitational field. The centrifuge is just magnifying that effect, so it happens faster.