Short Notes:

A lever is a narrow beam that rotates around a single point, called the fulcrum. By placing an object to be moved, called a load, at one point on the beam and applying an effort at another point, a person can move the object far more easily than by picking it up and moving it by hand.

Levers work by a simple formula: The effort multiplied by its distance from the fulcrum equals the weight multiplied by its distance from the fulcrum. The longer the lever arm, the greater the force amplification, and the easier it becomes to move the load. The price for this advantage is that the longer the lever arm is, the shorter the distance the load will move.

There are three classes of levers, which differ by the relative positions of the applied force, the load, and the fulcrum.