What Are Pulleys & Levers?
Pulleys and levers are simple machines that help to make daily work easier. They do so by reducing the amount of effort needed to complete a task by utilizing mechanical advantage (leverage). These simple machines are the building blocks for more advanced machines. Does this Spark an idea?
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First-Class Levers
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A seesaw is a first-class lever. First-class levers are the most familiar to people. This lever has a fulcrum in between, while the applied force and load are at opposite ends. This allows for a small amount of applied force to lift the load. The greater the distance between the force and the fulcrum while decreasing the distance between the fulcrum and the load allows for a greater mechanical advantage, making the lifting of the load easier.
Second-Class Lever
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Nutcrackers are second-class levers. The second-class lever has the fulcrum at one end while the applied force is at the other. The load is applied between them. This lever causes the load to move in the same direction as the force applied. The closer the load is placed to the fulcrum the greater force applied on the load.
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Third-Class Lever
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Your arm is a third-class lever. The third-class lever is the one used most often. The fulcrum is at one end of the lever, and the load is applied to the other end while the force is applied between the fulcrum and the load. This lever can not give any mechanical advantage. No matter where the load is placed, the force must exceed the load. This lever allows for movement of the load in the same direction as the force applied.
Pulley
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Common simple pulley. A pulley is a simple machine that has a wheel with a grooved lip that allows a cable or rope to run along the groove. The load is attached to one end while the force is applied to the other end. A pulley does not relieve the required force to move the load but rather changes the direction of the force being applied to allow for greater leverage.
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References
Resources
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