Lesson Plan - Get It!
What do this man and an elevator have in common?
The boy in the picture above is using a pulley to help him lift the heavy barrel.
A pulley is a simple machine that does a job that a single human being may not be able to do. Moving or lifting very heavy objects can be too difficult for one person to do on his or her own, so he or she can use tools to help.
If you missed the Related Lessons in this Simple Machine Fun! series, find them in the right-hand sidebar.
A pulley is actually very simple. All you need is a wheel and a piece of rope looped around the wheel. Now, the wheel does need to be secured in place — preferably a high place if you're trying to lift a heavy object — if it is going to work properly. One end of the rope is fastened to the object you are lifting, and you pull on the other end. The rope glides over the wheel, which turns in the same direction. As the wheel turns, it helps reduce the amount of force needed to lift the object.
As you learn about the uses of pulleys, fill in the Graphic Organizer 2 Column Chart sheet found in Downloadable Resources in the right-hand sidebar. An example has been done for you.
Pulleys have been used to help people lift things for more than 3,000 years! People needed a way to move things like water from a river to their home, and heavy logs from the forest to where they were building their home.
Another example of a pulley that you may have seen, or maybe even used, is a flag pole. In this instance, you can stand on the ground and move the flag far up into the air by pulling on the chain or rope.
If you have curtains or blinds in your house, that cord you pull that makes them move is looped over a wheel, which makes it a pulley!
Pulleys are pretty simple, but depending on how they are used, things can start to get a little complicated. For example, some pulleys have multiple wheels. Other pulleys use weights on the other side, called counterweights. An example of a pulley system that uses counterweights is an elevator. We can get into more complicated pulley systems in another lesson.
There are literally thousands of uses for pulleys in your world. Can you think of any other uses for pulleys? Check out What is a Pulley? - Simple Machines | Mocomi Kids (below) to explore more about pulleys. This video will help you understand how a pulley works, and how the effort used to move a heavy load can be lessened with a pulley system:
Another great resource is the Kloonigames Ltd. website, Crayon Physics. Feel free to explore simple machines on this website as well.
In the Got It? section, you will get to put your knowledge to work to be creative and write your own story!