Answer:
When finding the ideal mechanical advantage (IMA), the negative force not being included is friction.
Step-by-step explanation:
Mechanical Advantage is the ratio between the force exerted by a mechanism and the force applied to it. The simplest example is the lever, where the ratio of forces is equal to the ratio between the lengths of the lever arms. Another example is the system formed by rope and pulley. If the rope passes twice between the upper and lower pulleys, then the mechanical advantage is four to one.
In situations where the ideal mechanical advantage is found, there is a negative force not included, that force is friction.