Homework Sourseblood is placed in a centrifuge of radius 150 cm The mass of
blood is placed in a centrifuge of radius 15.0 cm. The mass of
a red blood cell is 3.0 × 10–16 kg, and the magnitude of the force acting on it as it settles
out of the plasma is 4.0 × 10–11 N. At how many revolutions per second should the
centrifuge be operated?
a red blood cell is 3.0 × 10–16 kg, and the magnitude of the force acting on it as it settles
out of the plasma is 4.0 × 10–11 N. At how many revolutions per second should the
centrifuge be operated?
Solution
F = m ^2 r where m is the mass, w the angular velocity in rad/s and r the distance of the sample from the rotation axis
solving for :
=sqrt[F/mr]=sqrt[4x10-11N/{3x10-16 x 0.15m}]
=942.8rad/s = 150.1 rev/s [since there are 2 pi radians / revolution]
At 150.1 rev/s the centrifuge should be operated
