One of the most useful simple machines is the screw. A screw is an inclined plane wrapped around a central post into a spiral shape. The ridges of a screw are the inclined plane. The ridges start at the bottom of the post and wrap around many times until they reach the head of the screw.
Visit the links below. They provide more elaborate information on the definition of a screw, explain what it is used for, and shows some everyday examples of this simple machine!
Screws can do two things. First, they can convert a force that goes around and around into a force that goes up and down, such as a cider or grape press. Second, screws can thread into things like wood or a metal bolt so that the two things are interlocked and can't come apart. When you drive a screw into wood, the wood moves up the inclined plane. Ridges on drills and bolts are other examples of screws.
Let’s think about it - a screw is like the ramp, and the width of the thread is like the angle of an inclined plane. The wider the thread of a screw, the harder it is to turn. If you've ever screwed in a screw with really narrow threads, you've probably found that you have to turn it a really long time in order to make it move. Just like a ramp, the easier the effort, the longer the distance you have to move something!
Take a look at some examples of screws. Do you or have you used screws in any of these ways before? Which do you most? Are there any that surprise you?