Gears can help us do work by speeding up or changing the direction of motion. To see how this works, make a model set of gears!
What You Need:
You've just built a gear train. The big gear is the driver. Try turning it slowly. What happens to the little gear? Which way does it turn? Draw a big colorful dot on each gear, and position the gears so that both dots are at the top. As you turn the big gear, have one person count how many times the big gear turns all the way around and another person count how many times the small gear does. Do they turn the same number of times?
Gears work to change the direction of motion. When you turned the big gear one way, the little gear turned the other way! Gears also change speed of motion. When you turn the big gear slowly, the smaller gear turns faster. This helps save energy, because you don't have to work as hard to turn the big one slowly as if you had to turn the small one quickly.
You can also try this project with water bottle caps that have ridges, or with gears from a building set like Lego or K'Nex.
An inclined plane, such as a ramp, is a kind of simple machine that helps do work. A screw, just like the ones from a hardware store, is also a simple machine! A screw is made from an inclined plane being wrapped around and around. To see how this works, you will need notebook paper, and a pencil or marker.
Because of the inclined plane, screws can hold all sorts of things together. If you like, try making different shapes and sizes of triangles, and wrap them around a marker or pencil to make different kinds of screws.