While your child may not believe in UFOs, she can still mimic the unique alien vehicle popularized by films and television. That type of friction-free movement does, in fact, lie at the heart of hovercraft technology. This experiment lets you use everyday objects as a gateway to this brave new world of transport.
In this experiment, air rushes out of the balloon through the hole to provide an air cushion below the CD. This cushion supports the entire lower surface of the CD because air is escaping on all sides. And without the friction created by rubbing against the table surface (the air cushion has eliminated it), the “hovercraft” can move freely. The same principles enable real hovercrafts to transport passengers and cars across open water.
Elapsed time: 2–5 minutes
What You Need:
- Sharp scissors
- Plastic bottle cap
- Strong glue
- Ordinary CD or DVD
- 7- or 8-inch balloon
What to Do:
- Make a ½-inch hole in the center of the cap by piercing it with the scissors. Slowly rotate the scissors, widening the hole, until it is ½ inch across.
- Have your child glue the flat side of the cap to the center of the CD or DVD so that the holes align, and let the glue dry.
- Ask your child to blow up the balloon and twist the end tight (but do not tie it off ).
- Carefully roll the balloon’s “lip” over the edge of the cap.
- Place the CD or DVD on a smooth surface and release.
- The miniature hovercraft should slide easily along the surface with just the slightest touch.
Be careful not to use too much glue when attaching the cap to the CD (you might block part of the hole).
By Sean Connolly
Adapted with permission from "The Book of Totally Irresponsible Science." Copyright 2008 by Sean Connolly. Used with permission of Workman Publishing Company, Inc., New York. All Rights Reserved.
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