How Do You Make a Single Fixed & Single Movable Pulley?

Movable pulleys move as they lift.

Pulleys are simple machines. A fixed pulley is attached to a base, and while its wheel turns when used, the pulley itself remains immobile as the line looped over its grooved wheel lifts an object. A movable pulley moves with the load it lifts, with the line looped underneath the grooved wheel and secured to a base. Pulleys are widely available, and can be purchased at hardware stores and hunting gear outlets. Pulleys with hooks or metal rings attached are the easiest to use.

Things You'll Need

• 2 grooved wheels with attached hooks
• Twine
• Scissors
• Fixed pulley

Instructions

Fixed Pulleys

1. Suspend one grooved wheel from an unmovable fixture -- a stair rail or a tree branch, for example -- by using twine to tie its hook to the fixture.

2. Cut a piece of twine to the length needed for the pulley's intended use.

3. Thread the twine over the top of the grooved wheel.

4. Attach one end of the twine to the object to be lifted.

5. Pull downward on the other end of the twine.

Movable Pulleys

1. Tie a piece of twine to an unmovable fixture.

2. Thread the twine underneath the grooved wheel so that the wheel's hook hangs downward.

3. Attach the object to be lifted to the hook.

4. Pull the free end of the twine upward.

Tips & Warnings

• Pulleys are rated according to the weight of the loads they can lift. Never use a pulley to lift a load heavier than the pulley's lifting capacity.

References

• Physical Science Lab Manual: Compare Pulleys
• The Office: Pulley Basics
• Thomas Jefferson Lab Science Education: Work and Simple Machines
• Franklin Institute Science Museum: Understanding Simple Machines: The Pulley