Which factor does NOT affect the AMA of a lever?

The actual mechanical advantage (AMA) of a lever is influenced by various factors that contribute to its efficiency and effectiveness. Friction is a significant factor because it creates resistance that can reduce the output force compared to the input force applied. The load applied also directly affects the AMA, as a heavier load requires more effort to lift, thereby impacting the effective mechanical advantage. Additionally, the effort exerted influences the mechanical advantage because it determines how much input force is used to overcome the load.

The length of the lever arm, however, does not directly affect the AMA itself in a way that the other factors do. The AMA is calculated based on the actual forces acting on the lever (the load and the effort) rather than the physical dimensions of the lever. While the length of the lever arms can affect the mechanical advantage in terms of ideal scenarios (as seen in the calculation of ideal mechanical advantage), it does not impact the actual mechanical advantage when considering the real-world effects like friction and internal forces. Therefore, the length of the lever arm is the factor that does not directly affect the AMA.