The working principle of the centrifuge When the suspension containing fine particles is stationary, the suspended particles gradually sink due to the action of the gravitational field. The heavier the particles, the faster they sink, and vice versa, particles with a smaller density than the liquid will float up. The speed at which particles move in a gravitational field is related to the size, morphology, and density of the particles, as well as the strength of the gravitational field and the viscosity of the liquid. The sedimentation of particles the size of red blood cells, a few microns in diameter, can be observed under normal gravity.