Emergency! White water rafters have overturned their raft, and the speeding current is pulling them toward a waterfall. A helicopter zips in and lowers the rescue bucket. The distressed rafters climb in and are pulled to safety. What simple machine is at work in the helicopter bucket? Here's a hint: it involves a wheel, groove, and rope. If you said pulley, you're right! In this project, you'll use paperclips and string to make a pulley.
The helicopter bucket uses a pulley. Think of other examples of pulleys. Some that you might have seen are a construction crane, elevator, flag pole, old-fashioned water well, and exercise machines. Can you think of any others?
To simulate a helicopter rescue by making a simple pulley from household items.
- 2 paperclips
- 36 inches of string
- Plastic berry basket
- Small figurine
- Notebook and pencil
- Unbend the center of a Paperclip 1 so that it makes a hook.
- Tie Paperclip 1 to the end of a piece of string.
- Thread the loose end of the string through Paperclip 2. You just made a pulley!
- Put the figurine in your berry basket, and place both on the ground.
- Now, lower Paperclip 1 to hook the basket.
- Pull the loose end of the string through Paperclip 2, raising the basket.
Your helicopter rescue was a success! You created a pulley using paperclips and string, and you used your pulley to lift a basket.
Pulleys are all around us. Look at your window blinds. Notice that when you pull the string down, the blinds go up. This is a pulley at work. A pulley is a simple machine used to make lifting easier. If you drop your book on the floor, you can bend down and pick it up, no problem. When it comes to putting a roof on a house, though, construction workers can't just bend down and pick it up since it is so big. A pulley allows the work to be done from a crane; the machine construction workers use to lift heavy materials. The force in the crane pulls down, and the roof goes up. Pulleys are useful tools that can even be life-savers. Just ask the white water rafters!
Now that you're a pulley expert, it's time for more guessing and testing. Think about the strength of the different parts of the pulley: What other items do you think you can lift? How many can you pick up? Which would be easier to lift with your pulley: a book or a doll? Can your pulley be used to move things from side-to-side, or just straight up and down? Write down any guesses that you have, called hypotheses, in your notebook before testing your new problems.
Keep thinking like a scientist, and you can conduct endless investigations with your paperclip pulley.