Theoretical mechanical advantage can be calculated as the ratio:

• A. Weight:Force
• B. Load:Weight
• C. Load:Force required to move load
• D. Load:Weight of anchor

Answer: (C)

Theoretical mechanical advantage is about how much a machine multiplies your input force. It is defined as the ratio of the load (the resistance you’re trying to move) to the force you must apply to move that load, assuming ideal conditions with no friction or losses. In other words, MA_th = Load / Force required to move load.

If you have a 1000 N load and you need only 200 N of effort to move it, the MA_th is 5, meaning the machine makes the work feel five times easier. This formulation uses the load (the resistance) and the actual effort, which is why it’s the correct way to express the theoretical advantage.

The other options don’t fit because they either mix terms that don’t represent the input effort (such as comparing weights, or referencing the anchor) or they don’t pair the resistance with the actual effort needed to overcome it.