Thursday, October 1st, 2009

Before Recycling: Educational Fun with Two-Liter Plastic Bottles

cola_bottleSeveral weeks ago my wife and I decided that it was time to take a road trip. Considering that we are not too fond of crowds, it was surprising that we ultimately decided on Niagara Falls. At least it was off-season. While gazing at a few million gallons of water flowing off of a tall cliff was definitely beautiful and awe-inspiring, after the eight hour drive, my wife thought it would best to check-in to our hotel and rest for a little while. Then we saw rockets fly!

Get your mind out of the gutter.

Actually, I caught a really cool episode of  This Old House on PBS that included a segment on how to build a water rocket and launcher.  While This Old House is not usually my type of show, I was fortunate to have caught this particular episode.  The project basically uses a plastic two-liter bottle, some PVC (polyvinyl chloride) pipe, some plastic zip ties, and a few PVC fittings. In fact, besides a metal hose clamp, a rope, a tire valve and an air pump, the entire assembly was made of plastic.

You can read and see the step-by-step instructions here.  (The middle school teacher who developed the project has his own more detailed instructions.) Judging by the vast majority of comments on the side of the web page — including those from parents, teachers and cub scout/girl scout leaders – the one to two  hour project is easy to do and a big hit with kids.

It's always nice to show off the educational and entertaining side of plastics and use plastic materials to teach kids basic ideas concerning design, engineering, and physics. .

Here’s another fun experiment (though perhaps not ideal for small children) that uses Mentos candy dropped into a full two-liter plastic bottle of Diet Coke.  Check out this humorous video (one of many on the same theme) and then watch as the dudes from the Mythbusters show explain how the rough, dimply surface area of the Mentos is one key to the explosiveness.  Here’s a far more thorough explanation of the science behind the reaction provided by a physicist at Appalachian State University.


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