Lever

Lever

A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. It is one of the six simple machines identified by Renaissance scientists drawing from Greek texts on technology.

Principle of levers

The principle of levers, also known as the law of the lever, states that the distance from the fulcrum to the point of effort is inversely proportional to the distance from the fulcrum to the point of resistance. This principle is used to determine the mechanical advantage of the lever.

Types of levers

There are three classes of levers, depending on the relative positions of the fulcrum, the load and the effort.

First-class levers

In a first-class lever, the fulcrum is located between the effort and the load. Examples of first-class levers include seesaws, crowbars, and pliers.

Second-class levers

In a second-class lever, the load is located between the effort and the fulcrum. Examples of second-class levers include wheelbarrows, nutcrackers, and bottle openers.

Third-class levers

In a third-class lever, the effort is located between the load and the fulcrum. Examples of third-class levers include tweezers, brooms, and the human arm.

Applications of levers

Levers are used in a wide variety of applications, from simple tools to complex machinery. They are used to amplify an input force, change the direction of a force, or increase the speed or distance of a force.

See also

• Simple machine
• Mechanical advantage
• Fulcrum (mechanics)

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