o The pulley is a simple machine consisting of a grooved wheel in which a pulled rope is run.
o Four paper clips
o sand
o Plastic Cup
o String
o Spring balance
o Yardstick
o Two Chairs
o A single fixed pulley
1. Explain to the children that in order to understand how a pulley works, we are going to construct a model of a pulley-like system.
2. Put a rubber band around the mouth of a cup
3. Unbend 3 paper clips into !S! shapes.
4. To create a !bucket! attach two !S_! shaped paper clips on opposite sides of the rubber band around the cup and hook them to each other over the cup.
5. Tie a string to the intersection of the hooked paper clips.
6. Using short length of string, attach a third paper clip to a yardstick supported between two charts.
7. Using a short length of string, attach a third paper clip to a yard stick supported between 2 chairs.
8. Run another string through the paper clip that is tied to the yardstick. Attach one end of the string to the bucket and the other end to a spring scale.
9. Add sand to the bucket. Have the children pull down on the starting by holding on the spring scale. Have them observe the amount of force indicated on the spring scale.
10. Have students test the scale by picking things up with a paper clip pulley and without a paper clip pulley. Have them use the spring scale to measure the amount of force needed.
11. In order to demonstrate the activity using an actual pulley, do a demonstration of the above, replacing the top paper clip with a single fixed pulley.
A pulley is a wheel with a groove in its rim through which a rope or chain is drawn. A single fixed pulley does not increase force, it changes the direction of the force. Some common pulleys can be found in: window shades, wells, cranes, bicycle pedals, flagpoles and elevators.
For more information on this subject click on the links below:
Phoenix Manufacturing of Pulleys
http://www.dredgemag.com/august/synop1.html
This webpage was created by Francisco, a participant in the Miami Museum of Science's UniTY program. This activity was adapted from lesson plans created by Museum education specialists, and is intended for use by parents and teachers to engage children in environmental education activities.