Whether it is for a school project or to help you with moving things in your house, a pulley is a great gadget that has been around for centuries. Put your mechanical abilities to use and create your own pulley.
Determine the strength and size of the wheel or spool and cord you will use to lift the object. For this demonstration, consider lifting a pencil from a desk to the top of a cabinet by a pulley.
Bend the wire into a triangular shape, inserting the ends into an emptied thread spool, and attach the wire to a fixed object, such as a cabinet. The spool should turn easily.
Attach a paper clip to one end of the string, and hang the cord over the spool, leaving enough to reach the desk. Tie the pencil to the string.
Pull gently on the other end of the string that holds the paper clip, and watch the pencil be lifted to the cabinet.
Experiment with a double-pulley system. This is basically the same, but works with less effort from the operator of the pulley. Take two spools instead of one and run a cord around them, tying the ends together to create a loop. Put a pencil through the spools and affix the pencils to an object, making sure the spools can move. Write a message and attach it to the cord with a paper clip. Pull the cord to move the message from one end to the other. The more complex the pulley system, the less effort is needed to lift or move the object.
Explain the pulley system and the benefits of a more detailed pulley system to students. Have two people hold broomsticks. Tie one end of a rope to one of the broomsticks; wrap the other end around the second broomstick. Have your helpers try to pull them together by using the free end of the rope. Wrap the free end around the first broomstick again, and try to pull them together. Do it again, wrapping it around the second broomstick. This shows how a pulley works more efficiently the more loops it has. Once you get the concept, the pulley will be a great help to you in different scenarios.
- Charley Steward/Demand Media