Question

I was walking through my local home supply store the other day carrying a 10 ft length of plastic pipe. The pipe was horizontal and my hand was supporting the middle of the pipe. I noticed that when I took two steps each second the ends of the pipe would move up and down a large distance. If I walked a little slower or a little faster they did not. Explain why this happened. What is the physical phenomenon being represented here? Were the ends of the pipe nodes or antinodes? What other rates of walking might also cause increased vibration in the pipe?

Answer 1

The phenomenon was resonance and the ends of the pipe were antinodes. The length of the pipe was an integral multiple of 1/2 of the wavelength. Other integral multiples of the walking speed could cause resonances.