A sample of blood is placed in a centrifuge of radius 16.0 cm. The mass of a red blood cell is 3.0e-16 kg, and the magnitude of the force acting on it as it settles out of the plasma is 4.0e-11 N. At how many revolutions per second should the centrifuge be operated? I can figure out the velocity... but the answer needs to be in revolutions per second. Would I just divide the velocity by the circumference of the centrifuge??