In physics, a lever is a simple machine consisting of a rigid beam or rod pivoted at a fixed point called a fulcrum. Levers rely on torque for their operation, which is the amount of force required to cause an object to rotate around its axis or pivot point. The effort force and load force are applied to either end of the beam, and the location of the effort, load, and fulcrum determine the type of lever and the amount of mechanical advantage the machine has. There are three types or classes of levers, which are classified based on the location of the fulcrum, load, and effort:
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First-class lever: The fulcrum is located between the effort and the load. Examples include seesaws, crowbars, and scissors.
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Second-class lever: The load is located between the fulcrum and the effort. Examples include wheelbarrows, brooms, and nutcrackers.
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Third-class lever: The effort is located between the fulcrum and the load. Examples include shovels, fishing rods, and tweezers.
Levers provide mechanical advantage, which refers to how much a simple machine multiplies an applied force. The farther the effort is away from the fulcrum, the easier it is to move the load, and mechanical advantage can be calculated using a formula. Levers are used in many tools and machines, and they are also found in the human body.
