how to separate two solids of different densities by a circular motion
Two solids of sufficiently different densities can be separated from each other by using a Centrifuge. It is a device in which a mixture can be rotated at high speeds around a fixed axis. The centrifugal forces thus generated will cause separation of solids based on their densities. The solids with higher density will be deposited near the edge of the centrifuge container, while the lighter solids will be concentrated near the center of the container.
The assumption here is that the particles will be discrete and thus free to move (i.e., will not be sticking to each other). Another method of separating solids of different densities is by agitating them in a container. This can be done by manual shaking or rolling. This will also cause solids separation, with denser particles occupying position under the lighter particles.
Hope this helps.
check Approved by eNotes Editorial