Beads on Rotating Arms

When the arms (rods) are at rest, the beads remain stationary at the bottom of the arms. On setting the arms into rotation the beads slide along the arms and remain stable at some height depending on the speed of rotation. The beads rise until their displacement from the central shaft, their axis of rotation, is a maximum. Speed Governors that are used to limit the maximum speed of heavy duty vehicles work on this principle.