When one person sets their swing in motion and then both persons allow the swings to move freely, you can observe a vibration transfer phenomenon. Swing that up to this moment was still, starts to move back and forth with increasing amplitude. At the same time amplitude of the first swings’ movements is decreasing. After some time, the process repeats. This phenomenon does not occur indefinitely because of motion resistance in the system. Coupled swings refer to the harmonic oscillator model which is used to study mutual influences of two bodies. Dependences discovered by this model are the basis of particle physics.