Wednesday, October 21, 2009

Spool Tractors - Rubber Band Powered Racing Machines

We've been in an old fashioned mood this week. So, when faced with a gray rainy morning (the snow is completely gone, and we've traded the arctic cold, for a Pacific Northwest drizzle), we turned to our trusty World Book Child Craft "Make and Do" volume, for entertainment.

The children wanted to try out a spool tractor. I was going to say no, after all, the instructions called for an empty wooden spool, a stick match, a piece of bar soap, a rubber band, and a small nail. Old fashioned is one thing, but even if I could locate a piece of bar soap, or a wooden spool in the house, I certainly wasn't going to hand over a stick match, and small nail to a bunch of bored and restless children. I'm not completely crazy.

However, after a quick look online, I was satisfied, that we could make some substitutions, and still come out about the same.

For our first tractor, we followed instruction from How to Make Anything. It called for a modern spool (with or without thread), and replaced the nail with a paper clip, the soap with petroleum jelly, and the match stick with half of a clothes pin. You can click the link above for a how-to video, or just figure it out from the pictures below.

Once we had it assembled, we turned the clothes pin, to wind the rubber band, and let it go.

It went a little ways, but not as far as we would have liked, and I couldn't help but to wonder, if the older version in our World Book, wouldn't have worked better. I decided to wipe off the Vaseline, and replace the clothes pin with a chunky crayon (one of our homemade crayons, to be specific), figuring the waxy crayon would reduce the friction, the same as a piece of soap, and it's shape would keep it from turning all the way around, thus turning the spool instead.

It worked great. I put paper down, in case the crayon left a mark behind, but thanks to the inferior nature of my homemade crayons, it didn't really leave any mess. Our new tractor, would start out with a burst of speed, seem to stop, rock a little, and then inch forward, a bit at a time.

We made a second tractor, and raced them. As they inched forward, it was impossible to tell which one would cross the finish line first. Add in a lot of cheering, and clapping, and it made for a pretty exciting morning.

Of course, there's a science lesson under all the fun too, about potential and kinetic energy, or maybe friction and inertia. Basically, Newton in a nutshell. But for today, we're just having fun.

It's great to be a homeschooler.

1 comment:

Kez said...

Cool - I've seen projects that use the old fashioned wooden spools and wondered what on earth I could substitute!