WOLFRAM|DEMONSTRATIONS PROJECT

Bead on a Horizontally Rotating Hoop with Movable Axis

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animate
manual control
rotation frequency
rotation axis shift
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This Demonstration illustrates the behavior of a bead sliding with very minimal friction on a circular hoop as the hoop is rotated about a horizontal axis that can be shifted up or down. The behavior of the bead in the rotating frame of the hoop illustrates the principle of ponderomotive traps, such as the Paul rf trap and the Penning trap, used in atomic and molecular physics. Such traps display parametric stability, so that the particle is kept near its equilibrium position only for certain values of the parameters. In this Demonstration the variable parameters are the frequency of rotation and the vertical shift of the axis of rotation.