#kinetic sculpture #math #physics #video

A mesmerizing pendulum wave demonstration with 16 bowling balls in a North Carolina forest

September 9, 2014

Christopher Jobson


If you’ve ever been to a science museum or taken a physics class, you’ve probably encountered an example of a pendulum wave. This video shows a large-scale pendulum wave contraption built on private property in the mountains of North Carolina, near Burnsville. The mechanism relies on 16 precisely hung bowling balls on a wooden frame that swing in hypnotic patterns for a cycle of about 2 minute and 40 seconds. Via Maria Ikenberry who filmed the clip:

The length of time it takes a ball to swing back and forth one time to return to its starting position is dependent on the length of the pendulum, not the mass of the ball. A longer pendulum will take longer to complete one cycle than a shorter pendulum. The lengths of the pendula in this demonstration are all different and were calculated so that in about 2:40, the balls all return to the same position at the same time – in that 2:40, the longest pendulum (in front) will oscillate (or go back and forth) 50 times, the next will oscillate 51 times, and on to the last of the 16 pendula which will oscillate 65 times.

Because the piece is outdoors, a number of factors prevent the balls from precisely lining up at the end, but it’s still easy to get the idea. In a perfectly controlled environment you get something like this.

Update: The pendulum was built by Appalachian State University teacher and artist Jeff Goodman.



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