3B10.u1 - Waves Traveling through Different Media
To demonstrate a transverse wave travel through a suspended slinky of a single type of material vs. a slinky of two different types of media.
Attach two bench clamps to the catwalk and feed the support rod for each of the slinkies so that they hang about 4 feet apart from one another. There is a string fed through the center of the slinkies. This is used to slowly lower the slinkies down from the catwalk. When completed with the demo, slowly bring up the slinky while leaving the string hanging down. Once all of the slinky is collected, take the hanging string and use that to secure the slinky.
The effect is more obvious if you can send a wave up both slinkies at the same time. Just quickly displace the bottom of the slinkies to create a pulse that will travel up the slinky, get reflected, and come back down. For the slinky that is all one type of material, you will see a pulse travel just as was described. For the slinky that is two different types of material, at the boundary between the two types there will be a reflection of the incoming wave as well as the reflection from the top of the suspended slinky. Since the metal slinky is more dense than the plastic slinky, the wave that passes through two different types of slinkies will reach the bottom faster than the slinky only made of plastic.