# What is a lever? Part 3

Levers
By: Laurel M.

The Basics:

A lever is what we call a simple machine. A lever is one out of the six simple machines, and it was the first one to be invented.
Levers are used for applying force, and are actually everywhere and you don’t even know it!A couple of examples of levers are a see saw or a pair of pliers. Both of these objects are levers.
 Above is a picture of a hand pushing down on a lever.

As you can see in this picture the fulcrum is the triangle and that is what holds the lever stick (in this picture the straight line) and
what allows the lever stick to move back and forth. The hand pushing down on the lever stick is called the force and the rock is the
load, because the hand is trying to push down to try to move the rock up, and the rock is the load because it is the weight that the
lever is holding, so force is any push or pull, and load (load is sometimes called resistance) is whatever is being pushed or pulled.
So the hand is trying to push down on the lever so the rock will lift up off of the ground. If the load is closer to the fulcrum than the
force it can be lifted with less effort.

 Above is a diagram to explain what a lever is.

1st, 2nd, and 3rd Class levers:

There are three different types of levers. First, second, and third class levers.
First Class Lever: A first class lever is when the fulcrum is between the resistance and the effort.
Second Class Lever: A second class lever is when the resistance is between the fulcrum and the effort.
Third Class Lever: A third class lever is when the effort between the resistance and the fulcrum.
 above is a picture to represent a 1st class lever.

A see saw is a first class lever because there is a fulcrum between the resistance (load) and the effort (force).The kid at the bottom of the see saw is the load and the kid at the top is the resistance.(or it can be the other way around) the thing in the middle is the fulcrum.Since the fulcrum is between the resistance and the load it is a first class lever.

Examples: First Class Lever: An example of a 1st class lever is a see saw
Second Class Lever: An example of a 2nd class lever is a nutcracker
Third Class Lever: An example of a 3rd class lever is a rake

More Examples:
Another Example: if a hammer is driving a nail into a board it is a third class lever because the effort is the hand and the resistance is the hammer and the fulcrum is the lower hand. Since the effort is in the middle of the fulcrum and the resistance it is a 3rd class lever.
Another Example: If you were trying to get the nail out of the wooden board it would be a first class lever because the nail is the resistance, the hand is effort, and the fulcrum is located someplace in between the resistance and the effort, making it a first class lever.
All levers have something in common. They all involve a force, called the effort, which moves a load, making use of the fulcrum.

Glossary:
Force- Any push or pull
Load- The weight that the lever holds
Lever Stick- The part of the lever that can move back and forth, and holds the load
Fulcrum- The thing that holds the lever stick and allows it to move back and forth
First Class Lever: A first class lever is when the fulcrum is between the resistance and the effort.
Second Class Lever: A second class lever is when the resistance is between the fulcrum and the effort.
Third Class Lever: A third class lever is when the effort between the resistance and the fulcrum.