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What is a pulley?

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Quick answer

A pulley is a simple machine made of a wheel with a groove that a rope or cable runs over. It lets you change the direction of a force — pulling down to lift something up — and, with multiple pulleys, lift heavy loads with much less effort.

Key things to understand

  1. A single fixed pulley changes the direction of your pull (down to up) but not the force needed.
  2. Adding more pulleys (a block and tackle) spreads the load across several rope sections, so you pull with less force.
  3. The trade-off is distance: to halve the force, you pull twice as much rope.
  4. Pulleys are used in cranes, lifts, flagpoles, sails, and gym equipment.
  5. More supporting rope sections means greater mechanical advantage.

People also ask

How does a pulley make lifting easier?
A single pulley lets you pull down (easier, using your weight) to lift a load up. Multiple pulleys share the load across several rope sections, so each pull needs less force.
What's the difference between a fixed and a movable pulley?
A fixed pulley stays in place and only changes the direction of force. A movable pulley moves with the load and reduces the force needed, at the cost of pulling more rope.
Where are pulleys used?
Cranes, elevators, flagpoles, window blinds, sailboats, and weight machines all use pulleys to lift or move loads more easily.

Part of the guide: Everyday Machines →