PURPOSE: To create waves in a very dramatic way using a series of fifteen carefully adjusted independent pendula.

DESCRIPTION: After the pendula are started into oscillation with the same phase, they pass through a series of various standing wave and traveling wave patterns, finally returning to their initial mode, in which they were all in phase. This is a GREAT demonstration - takes about one minute.

SUGGESTIONS: Practice starting it so that the pendula continue to swing transverse to the support bar and do not hit each other.

REFERENCES: (PIRA 3B10.75) See Demonstration Reference File for article on our apparatus. The web site Pendulum Waves: A Lesson in Aliasing, by James Flaten and Kevin Parendo contains interesting computer simulations of this apparatus.

We have produced videos of the action in several formats:

• 8.0 megabyte mpeg Video (excellent quality)
• 1.8 megabyte Quicktime Video (poor quality)
• 870 kilobyte Real Media Video (good quality)
• 1.7 megabyte Windows Media Video (excellent quality)

other videos of this demonstration are available on the web:

• Arizona State University PIRT hallway display (very slick video).
• Harvard University Natural Sciences Lecture Demonstrations.

EQUIPMENT: As photographed.

SETUP TIME: None.