# The Purpose of Pulleys

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Pulleys belong to the simple machine category. Simple machines use mostly energy to work and require few parts. Some use no external parts to work, such as an inclined plane, a lever, or a screw. Typically, you use pulleys to lift heavy weights up to great heights. Without pulleys, raising heavy weights proves difficult.

## Origin of the Pulley

• Although the pulley's definitive origin remains undetermined, the Mesopotamian people used pulleys in 1500 to lift objects. Also, historians claim Archimedes, an infamous inventor and mathematician, invented a version of the pulley around 287 B.C. He knew that a person obtains a mechanical advantage when using a pulley, and he calculated a pulley's force with a method similar to what physicists do today using rope.

## A Pulley's Purpose

• A pulley's main purpose is to alleviate hard work. This is done through energy, ropes, and a grooved wheel. Essentially, the more pulleys or wheels involved, the lighter the work load because rope moves through more than one simple machine. A modern-day example of the pulley is a crane. You use a crane to lift steel bars up to great heights when building an apartment building, for instance.

## How Pulleys Work

• The mechanical advantage is involved with the pulley system. You need an advantage when using pulleys because that defines how much work you complete using the pulley. To calculate this advantage, divide the load amount by the effort done by the pulley or pulleys. Pulleys also increase or decrease force amounts and can even change a force's direction.

## Types of Pulleys

• Pulleys consist of simple and complex systems. You use a single rope in the simple pulley system, which means the pulley remains fixed. When you pull the rope, the pulley does not move. However, pulleys are movable using the simple system. Attach a weight to the movable pulley. This way, you move the weight and pulley, as you pull the rope down, lightening the work load. In the complex system, you involve more than one rope, which dramatically decreases the work force, allowing you to add heavier weights.

## References

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