Question

What would cause the AMA of a machine to decrease?How could you increase the AMA of a machine?

Answer 1

The AMA is the quotient between the input and output forces and is given by:

$AMA=\frac{F_o}{F_I}$

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:

$F_oR_o-F_iR_i=0$

Adding the product of the input force and input distance:

$F_oR_o=F_iR_i$

Now, we divide both sides by the input force:

$\frac{F_oR_o}{F_i}=R_i$

Now, we divide both sides by the output distance:

$\frac{F_o}{F_i}=\frac{R_i}{R_o}$

Therefore, the AMA is:

$AMA=\frac{R_i}{R_o}$

Therefore, if in the lever we increase the input distance or decrease the output distance we would increase the AMA.