Double Pulley

You have learned how to make a pulley system. Making a double pulley is an extension of the single make a pulley system experiment. Follow the method below to make a double pulley science experiment.

Equipment needed to conduct double pulley science experiments

Similar to the other pulley science experiment, you only need wire, thread spools, string, a hook, and a bucket of load.

Method for making double pulley experiment

1. Make two wire triangles. Use about 1 foot 2 inches (35 cm) of wire for each one.
2. Attach two spools to each triangle.
3. Thread the string around the pulleys as shown in the diagram. Use about 6½ feet (2 meters) of string.
4. Attach the heavy load to the pulley as before.

Now answer the following questions about the double pulley system you just made.

• Is it easier to life the load with the double pulley?
• How much string do you need to raise the load 1 foot (30 cm)? Compare this to the number you recorded for a single pulley experiment.

Explanation of pulley experiment

The pulley with one thread spool allows you to lift a heavy load directly underneath the pulley. The double pulley means you have to pull only a quarter as hard, but you have to pull for four times as long.