The mechanical advantage of a block and tackle is determined by what?

• A. The weight of the load
• B. Rope diameter
• C. The length of rope
• D. The number of rope runs

Answer: (A)

Mechanical advantage in a block and tackle comes from how many rope segments share the load. Each supporting rope segment helps carry part of the weight, so more rope runs means you can lift with less input force. The diameter or length of the rope doesn’t set the advantage; they affect strength and practicality, not the number of load-supporting segments. The actual weight of the load determines how much force you must apply, but MA is the ratio of load to effort, independent of the load’s size. In real systems, friction at the pulleys reduces the ideal advantage, so the practical MA is slightly less than the simple count of rope segments.