VIE-BRAY-SHON! It can do a little, or it can do a lot. Louis Armstrong blows into his trumpet, causes the brass it’s made of to vibrate, and produces sweet, sweet jazz. Tectonic plates in our planet’s crust collide, causing vibrations that swell to an earthquake.
VIE-BRAY-SHON! Sometimes you don’t want any, sometimes you want a lot. A piece of machinery that vibrates more than it should can shake itself to pieces, so you swap out a few parts for Vespel CR-6100 equivalents to reduce the vibration. A guitar string that’s too tight will play the wrong notes, so you loosen it until it vibrates like it should, and you’re ready to rock and/or roll.
VIE-BRAY-SHON! There are many different kinds, but this Demo Science experiment will only help you explain one type of vibration to your students—the aforementioned seismic waves.
For Once, You DO Want to Drop the Ball
For this demonstration, all you’ll need are some pieces of flat (or flattened) cardboard, a bowling ball, and a chair or something on which you can safely stand. If you don’t own a bowling ball—what are you, a commie?! #merica
Clear a good sized open space in your classroom, then layout your cardboard. You’ll want it to cover a fairly large area, but also be multi-layered for added protection. So… you might need quite a bit of cardboard.
Ask for a handful of volunteers, then send one to each corner of your classroom, one kid to the hall just outside the door, and one kid a little farther down the hall. For that last one, make sure you don’t pick a kid who’s going to wander off and not come back. (Lookin’ at you, Kevin!)
Have the rest of your students place their hands flat on their desks and their feet firmly on the floor. Ask them all to shut their little pie holes for a while, so that vibrations from their ruckus won’t interfere with the science. While they’re busy not talking, they can, instead, pay the hell attention (Kevin!) and observe what happens.
Once everyone is in position and prepared, clamber up on the chair, hold your bowling ball out over your cardboard pad, and drop that sucker. What happens?
The Science of Dropping Heavy Stuff
Unless you really, really beef something here, the impact of the bowling ball hitting the floor will cause some vibrations. Not a perfect analogy for an earthquake, but close enough for government work.
And like an earthquake, those vibrations will feel different to people at different distances from the point of impact/vibration. The students closest to where you dropped the ball will feel considerably stronger vibrations than the kid standing in the back corner. It’s like the kid just outside the door just barely felt them; the kid down the hall probably felt nothing at all.
Have your students compare “notes” on who felt what and how it relates to a real earthquake’s epicenter and surrounding areas.