How is the efficiency of a simple machine calculated?

The efficiency of a simple machine is best calculated using the formula for mechanical advantage, which involves the actual mechanical advantage (AMA) and the ideal mechanical advantage (IMA). Efficiency can indeed be expressed as a percentage of the relationship between the output mechanical advantage and the input mechanical advantage. This is why the formula that utilizes AMA and IMA is essential for understanding how effectively a simple machine transforms input work into output work.

While other options may seem relevant, they do not specifically address the way efficiency is commonly calculated in the context of simple machines. For instance, the first option focuses on work output and input, which is important but does not specifically relate to mechanical advantage. The third option mentions forces, which again relates to a different aspect of machine operation. The final option about energy is applicable in other contexts but may not fully capture the mechanical workings of simple machines in the same way that AMA and IMA do.

Thus, using the relationship of AMA and IMA provides a clearer and more direct measurement of how effectively a simple machine is performing its intended function, ultimately yielding a straightforward calculation of efficiency in the context of mechanical systems.