PURPOSE: To illustrate a system with two pendular modes of oscillation.
DESCRIPTION: A ball is suspended by a string attached to another string which hangs from a support rod as shown in the photograph. In one direction the pendulum swings with a short length while in the orthogonal direction it swings with a much longer length. When the ball is moved in any other direction and released the resulting motion is a combination of these two orthogonal modes.
SUGGESTIONS: Both lengths are adjustable.
REFERENCES: (PIRA 3A80.13) See Demonstration Reference File for several interesting articles on bifilar pendula.
EQUIPMENT: Bifilar pendulum as photographed.
SETUP TIME: None.
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