Lever

Levers are primarily utilised for gaining a mechanical advantage. As an introduction to levers, there is a need to concentrate on the principles of levers that are used to shift or pick up weights. There are three types of levers; the first order, second order and third order. Any lever has three parts and are described as:

• The weight (or load) to be moved or lifted
• The force applied to do the moving or lifting
• The fulcrum, or pivot point.

1st Order Levers
In a 1st order lever, the fulcrum (or pivot point) is positioned in between the load to lifted (or moved) and the force applied.
An example of a 1st order lever is shown in Figure 1.
The length of the movement arm defines what the lever is capable of doing.


The Force Movement Arm (Figure 2) is the distance from the force applied to
the fulcrum. This is called the Mf.
The Weight Movement Arm (Figure 2) is the distance from the weight to the
fulcrum (it is the remaining length of the lever) and is designated as the Wm.
In order for the force to exactly balance out the weight, the force applied
multiplied the distance of the force movement arm must equal the load weight
multiplied by the length of the weight movement arm. As an equation:
F x Mf = L x Wm
To calculate how much a lever could amplify the force applied to make it work
against a certain weight, there needs to be a transformation of formula to:
w =
Wm
F x Mf
It means that by adjusting where the force is and where the weight is, the
amount of force to move the weight changes. This ratio is called a Mechanical
Advantage. To predict the mechanical advantage of the set-up, divide the length
of the force movement arm by the length of the weight movement arm. That is: