A lever with a long arm requires a smaller effort force. What principle is this an example of?

The principle illustrated by a lever with a long arm requiring a smaller effort force is mechanical leverage. This concept is rooted in the physics of levers, where the effectiveness of the lever is enhanced by increasing the length of the arm.

When a lever is utilized, the force applied at one end (the effort) is transformed to create a larger output force at the other end, allowing for a greater load to be moved with less effort. The length of the lever arm plays a crucial role in this process; a longer arm means that the same amount of force will produce a greater torque about the fulcrum, thereby lifting a heavier load with ease. This principle is utilized in various tools and machinery, improving efficiency in the application of force for lifting or moving objects.

Other choices do not accurately capture the essence of this principle. The work-energy principle pertains to the relationship between work done and energy changes in a system, while applied force ratio isn't a standard term used in mechanics. Pulley efficiency refers specifically to the mechanical advantage provided by pulley systems, but does not apply directly to the mechanics of levers. Hence, the concept of mechanical leverage is the most applicable to the scenario described.