Abstract
The method using air flow is investigated to dress particles in similar density from some sorts of same size particles. Each gravity centers of distribution of similar weight particle have to keep some distance on the gravitational section to get the effective result by this method. To acquire the distance between gravity centers, in the first place, the gravity centers must be defined. Then the purpose of this article is to state on the calculation method of gravity center.
A co-ordinate of gravity center can get from the equation of motion concerning a representative particle, because it can be considered that a curve put the points of gravity centers in a row is a path line of the representative particle.
Results gained by this way are examined by experiments used glass beads.
