The AMA is the quotient between the input and output forces and is given by:
Where:
![\begin{gathered} F_o=\text{ output force} \\ F_I=\text{ input force} \end{gathered}]()
Therefore, the AMA is decreased if the input force is increased. If in a machine the friction force increases due to low maintenance then the required input force would increase and therefore, the AMA would decrease.
In a first-class lever we have the following:
We can calculate the ratio between input and output forces by adding the torque around the fulcrum:
Adding the product of the input force and input distance:
Now, we divide both sides by the input force:
Now, we divide both sides by the output distance:
Therefore, the AMA is:
Therefore, if in the lever we increase the input distance or decrease the output distance we would increase the AMA.