Which option correctly represents the mechanical advantage formula?

• A. MA = input force / output force
• B. MA = a function of distance
• C. MA = output force / input force
• D. MA = load / weight

Answer: (C)

Mechanical advantage is the factor by which a machine multiplies your effort, expressed as a ratio of the output force the machine provides to the input force you apply. That makes the correct form output force divided by input force, because it directly measures how much force the machine delivers to the load for a given input.

If you push with 100 N and the machine delivers 300 N to the load, the mechanical advantage is 3, showing a threefold increase in force. The other ideas mix up the concept: taking the inverse of the ratio would describe a mechanical disadvantage, not advantage; stating that MA depends simply on distance ignores the fundamental force ratio; and comparing load to weight isn’t the standard definition, since weight is a force and the ratio wouldn’t universally describe the advantage you gain.