We would now like to prove that each group of particles Gj describes a circle on the ground with a variable radius. In order to see this, let us consider equations (10a) and (10c) for τ = τ j and write
We would now like to prove that each group of particles Gj describes a circle on the ground with a variable radius. In order to see this, let us consider equations (10a) and (10c) for τ = τ j and write