Singing Tube Science

Being a homeschool teacher, and so naturally, or perhaps by necessity, fond of kitchen chemistry, I have a hard time walking through the grocery store, without making a mental list of potential projects.  There are exploding marshmallows for the microwave, and electrically charged Jell-O in with the baking goods, anthocyanin and bromelain in the produce aisle,  and so on, and so on.

My grocery store finds have not been limited to chemistry either, there are plenty of supplies for biology and physics labs to be found in among the Pop-tarts and laundry soap, as well.  Even the cheapy little toys, placed temptingly at child-eye level, offer scientific promise, such as the sound tubes I encountered in an end aisle display, on one of our latest shopping trips.

Remember those toys - they were big in the '70s. I had one myself, and it was great fun.  Spin them in the air  above your head, and they "sing".  Spin them slow, and the tone is low, spin them faster, and tone rises higher and higher.  That's a science lesson in and of itself...

...but we used ours to demonstrate the Bernoulli effect - that where there is fast moving air, there is low pressure (see this video lesson by Professor Gizmo for a more thorough explanation of the principle).

We secured a plastic bag to one end of the tube with a rubber band, and filled it with air (thanks to Steve Spangler for this idea).

Then, we spun the other, open end - so the air was moving quickly by it, creating an area of low pressure...

...that the higher pressure air, in the bag at the other end, wanted to fill...

 ...leaving us with an empty, fogged up (think cloud experiment), bag.

So, we turned the tube around, and spun the end with the bag on it.  Now, the low pressure was around the bag...

...which was quickly filled...

...by a flow of high pressure air from the stationary, open end, of the tube.

Not too bad for a $1.75 toy. Of course, when we were done experimenting, I removed the hazardous plastic bags, and let the children go off to make beautiful music for the neighbors to enjoy.

It's great to be a homeschooler.

Linked with Science Sunday at Adventures in Mommydom.