A lever is a simple machine that is made up of a board or bar that rests on an object. Levers are used to achieve a mechanical advantage, such as making lifting heavy objects easier.
Levers consist of three principal parts. The fulcrum is a solid board or rod that can pivot. The force is the physical effort applied to one end of the lever to make it move. The load is the item that is moved.
There are three types of levers. Each type, or class, of lever depends upon where the force, fulcrum and load are located. In a first-class lever, the fulcrum is located between the force and the load. An example of a first-class lever is a see saw. Scissors and pliers are double first-class levers. A second-class lever has the load located between the fulcrum and the force. A wheelbarrow is an example of a second-class lever. A third-class lever such as a fishing pole has the force between the fulcrum and the load.
Levers provide a mechanical advantage by increasing the force applied to an object or by increasing the distance an object is moved. The speed at which an object moves can also be increased by using a lever.