John’s Side Project: Fire!
For the last few weeks, John and his friend Roy have been working in their spare time on a neat physics demonstration to show off at the Texas A&M Physics Festival this coming weekend.
If you know what a standing wave is, you’ve probably seen the classic demonstration with a vibrating string. But did you know you can also trace out a standing wave in FIRE? True story.
The apparatus is called a Rubens Tube, after its kind-of inventor. It’s a long metal tube with small holes drilled along its length, filled with a flammable gas and set alight. When you pipe music into one end of the tube, the flames jump into different wave patterns.
Last night I got to stop by campus and videotape their progress. With a little pretending and a little video editing, we almost made it look like they built this contraption in a single evening.
Pretty neat, eh?
John made a website that explains a little more about how the Rubens Tube works. It’s got some nifty pictures, too.
There’s a tiny bit of smoke and mirrors here in that the explanation John gives on the site and in the video about higher pressure making taller flames is, at best, not the whole story. The truth is that the whole story is super complicated, and we can’t find a source that explains it clearly. But fifth graders don’t need to know that; “Sound is a wave” is a better takeaway message than “If you ask too many questions, science becomes really difficult and confusing.”
It reminds me of the answer to the question “How do airplanes fly?” that says something like, “Air has to travel faster over the top of the wing, and the Bernoulli Principle says faster-moving air has lower pressure, so the higher pressure underneath the wing provides lift.” It makes sense, but it’s mostly untrue. Nobody knows quite how airplanes fly. But they look cool doing it. And so does the Rubens Tube.
Tags: demo, demonstration, fun, John, physics, Rubens Tube, science, video
March 21st, 2010 at 4:05 pm
that is really awesome