A
lever is an object that is used with a fulcrum to multiply the mechanical force
that can be applied to another object. This leverage is also known as
mechanical advantage. The fulcrum is the point on which the lever moves. A
lever is one of the six simple machines, and also one of the most common.
The amount of work done is always the same.
The point where you apply the force is called the effort. Or the input force.
It's one of the most common because just about anything with a lever
attached to it is a lever. This brings us to the point of the three different
classes of levers. The three classes of levers represent the variations in the
location of the fulcrum and the input and the output forces.
First Class Levers:
A first lever is a lever where the fulcrum lies between the effort and the load. Or between the output force and input force. Some examples of first class levers are seesaws, trebuchets, crowbars, and scissors. A seesaw is an example of a first class elver because the fulcrum is in the middle of the board, and there's usually one person on each side. These people could stand for the effort and the output force. There is no mechanical advantage in this lever.
Second-class Levers:
In a second class lever the input effort is located at the end of the bar and
the fulcrum is located at the other end of the bar, opposite to the input, with
the output load at a point between these two forces.
Some examples of this lever are a diving board, wheelbarrow and a wrench.
A diving board is an example of a second class lever because as you step onto
the board, you are the load and it pulls down on the diving board. Then the
diving board's effort goes up there for it prevents you from just dropping
down. The fulcrum is the part where the diving board and its usual ladder
connect.
Third Class Levers:
Third class levers are levers in which the fulcrum is at the end and the input force is closer to the fulcrum than the output force. in a third class lever the mechanical advantage is negative, meaning the force required to lift the object is greater than it would be without the lever. The advantage of using these levers is it provides more movement to the object. so you may only need to move the lever one foot when the object moves two. This lever also multiplies the speed the object travels.
