WHAT IS A LEVER AND WHAT TYPES ARE THERE?

What is a lever?

A lever is a series of elements that are considered as a simple machine.  Practically it is a bar of any resistant material that is placed on a support in order to decrease the force necessary to lift any object.

Parts of a lever

As for the physical aspects of this machine, it practically has 2 essential components, which are the bar that is used to lift objects and a support that is also known as a base or fulcrum.

We can also find other parts of the lever, but these are more focused on the analysis part, such as we can find the resistant force or resistance (R), the acting force (F), the distance from R to the base (dR) and the distance from F to the base (dF).

Lever parts

Types of levers

Despite at first glance it can be said that there is only one type of lever, it is not entirely true since depending on where the resistance, strength and base are, we can find 3 different combinations which gives rise to three different types of levers.

First class lever

Practically it is the most common and used, its operation resembles that of a rocker since the fulcrum is placed in the midst of resistance and force.

Examples

The most common example is the game that children use to raise and lower «a rocker», but the base does not necessarily have to be right in the center of the bar, since as long as it is held between resistance and force it can be considered as first class, the ideal example is when we want to get a rock out of the way; The base sits just off the resistance but remains between the other two components.

First class lever

Second-class lever 

It is characterized by having the fulcrum on one end of the bar, the resistance is located right in the middle and the force is applied on the opposite side of the fulcrum.

Examples 

Within this type one of the simplest examples is that of a wheelbarrow, since the rim acts as a base, the tray or deposit as resistance and the force is exerted on the handle.

Second class lever

3rd class lever 

Within this type the elements are placed in the last possible way, the support is placed at one end, the resistance is just on the opposite side and the force is applied right in the middle of the bar.

Examples

In this type we can consider the tongs that are used to grab bread or meat, since the base is considered the union of these tongs, the resistance is the opposite side where the meat or bread is held and the force is exercised just in the middle of two.