In mechanical systems, what does a lever do to the input force?

A lever is a simple machine that allows one to amplify an input force to perform work more efficiently. The key characteristic of a lever is its ability to trade off force and distance; depending on the position of the fulcrum and the relative distances from it to the input and output forces, a lever can either increase or decrease the input force needed to lift a load.

When the fulcrum is closer to the load, a smaller input force can lift a larger load, which signifies an increase in force. Conversely, if the fulcrum is positioned closer to the input force, it requires a larger force to lift the same load, which means the input force is reduced in terms of its effectiveness. Therefore, levers can indeed increase or decrease the input force based on how they are utilized and the specific configuration of the lever system.

This versatility is what makes levers valuable in various applications, allowing a user to manipulate forces in a way that suits their needs, fulfilling the criteria in the correct answer choice.