Sunday, July 19, 2009

30 Second Science - Rubber Band Powered Boat

We did a quick little project yesterday, using old Altoids tin, a couple of popsicle sticks, two rubber bands, and a 2 and 1/2 inch by 1 inch piece of plastic, that I cut from a coffee can lid. I've been keeping an eye out for something fun to do with the Altoids tin, and finally came across this idea at It proved to be a great way to demonstrate potential verses kinetic energy, and Newton's third law of motion, not to mention, that it made a pretty fast little boat.

The steps for building are extremely simple.

  1. With the box closed, secure the popsicle sticks flat against the sides with a thick rubber band, so that about 1/4 to 1/2 of each stick is extending out beyond the end of the tin.

  2. Place a thinner rubber band across the ends of the sticks.

  3. Slip the piece of plastic through the thin rubber band.

  4. Twist the rubber band (storing potential energy in the twists).

  5. Place it in the water, and let it go (allowing the rubber band to untwist, and turning potential into kinetic energy).

  6. Show Newton's Law by having the children twisting the plastic paddle toward the tin, and letting the boat go, and then away from the tin, and letting it go. The boat is moved either forward, or backward, in an opposite reaction to the force of the paddle against the water.

Don't over twist the band, or it will break, but the more you twist it, the faster the little boat will move. Ours had a burst of speed sufficient to lift the nose of the craft out of the water.

It's great to be a homeschooler.

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