To determine the mechanical advantage of a third-class lever, one must calculate the ratio of the length of what two arms?

In a third-class lever, the mechanical advantage is determined by the ratio of the effort arm to the resistance arm. The effort arm is the distance from the fulcrum (the pivot point) to the point where the effort force is applied. The resistance arm is the distance from the fulcrum to the load or the resistance being moved.

In this case, when calculating the mechanical advantage, the focus is on how much effort is needed in relation to the load being lifted or moved. Specifically, the mechanical advantage formula for a lever states that it is the ratio of the length of the effort arm to the length of the resistance arm. Knowing this allows us to understand how efficient a lever is in amplifying the force applied compared to the output force that can be moved.

Third-class levers, such as a tweezers or a fishing rod, typically have the effort applied closer to the fulcrum than the load, resulting in a mechanical advantage that is less than one. This means that while they require more effort to move the load, they allow for a greater range of motion or fine control over the load being moved.