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Code Number: 3B10.75
Demo Title: Pendulum Waves
Condition: Excellent
Principle: Wave Motion
Area of Study: Oscillations & Acoustics
Equipment:
Multi-pendula wave demo, Aluminum angle starting bar.
Procedure:
Push the Aluminum angle starter bar against the pendulum bobs so that they are all displaced by the same amount. Quickly remove the bar and carefully watch the wave pass through various standing and traveling wave patterns before coming back to their initial mode in which they are all in phase.
The smaller unit made from fiber board and machine nuts as the pendulums is for use on the overhead projector.
Gerald Zani from Brown University offers this short explanation of what is a true wave machine.
References:
- Xiangdong Feng, Changhong Lu, Jurgen Schulte, Zengxu Shan, Gentong Liu, "Pendulum Waves: A Model of Thomae's Function", AJP, Vol. 91, #12, Dec. 2023, p. 964.
- James A. Flaten, Kevin A. Parendo, "Pendulum Waves: A Lesson in Aliasing", AJP, Vol. 69, # 7, July 2001, p. 778.
- Richard Berg, "Pendulum Waves: A Demonstration of Wave Motion Using Pendula", AJP, Vol. 59, # 2, February 1991, p. 186.
- Bobby Mercer, "Swinging Wave Machine", Junk Drawer Physics, p. 63.
Wave Machines - Gerald Zani - Brown University