Once you have learned the basics about how simple machines work, it's time to learn about compound machines. Compound machines are just two or more simple machines put together to achieve a specified result. For example, scissors are a compound machine, made up of a lever and a wedge. For a school project, make a complex machine using an inclined plane and a lever to propel a block into a cup, using basic materials you can find around the house.
To make this project easily transportable, consider using blocks instead of books, and glue down the blocks, the matchbox and the cup to a large piece of cardboard. To set up the project, you will only need to add the marble, the small block and the ruler.
Be careful when using the penknife; always point the blade away from your body and your fingers.
Place the ruler on the matchbox so that the matchbox is directly beneath the ruler's center. This will be your lever. Place the small block at one end of the ruler. The block should be no more than 1 cubic inch and should weigh as little as possible, made of cardboard, foam or other light material.
Use a penknife to scrape a thin, straight groove down the center of the foam board. This will mark the path that the marble will roll on.
Arrange two stacks of books, one higher than the other, and place the foam board on them so that one end is higher than the other. Roll the marble down the grooved line in the board and note where it falls.
Set the lever so that the empty end of the ruler lies exactly where the marble will fall.
Cut the top off the plastic cup so that the remaining bottom part is only an inch tall.
Roll the marble down the foam board so that it hits the ruler and propels the block into the air. Note where the block falls, and set the cup in that location to "catch" it.
- Rina Summer/Demand Media