PURPOSE: To demonstrate coupling of motion between two pendula of the same length.

DESCRIPTION: The pendula are hung from a rod which can rock back and forth to transfer the motion from one pendulum to another. If you start the pendulum at the left in motion (in and out of the picture), the motion will couple back and forth between the pendula of the same length, leaving the others with only a slight perturbation. It is of interest to note the phase of the two pendula as the motion is transferred back and forth.

SUGGESTIONS:

See Question of the Week #222 for information on using this demonstration to enhance class involvement.

REFERENCES: (PIRA 3A70.20) See Demonstration Reference File for information on our apparatus as well as a number of variations.

EQUIPMENT: Coupled pendula, as photographed.

SETUP TIME: None.