If a rescuer moved a load 50 feet using a simple 3:1 mechanical advantage, how much rope was pulled through the system?

• A. 50 feet
• B. 100 feet
• C. 150 feet
• D. 200 feet

Answer: (C)

In a simple 3:1 mechanical advantage, you must pull three times as much rope as the load moves. So if the load travels fifty feet, you would pull through the system three times that distance, which is one hundred fifty feet. This assumes an ideal, frictionless setup with no rope stretch; in real life, you’d pull a bit more rope to compensate for inefficiencies, but the theoretical amount is 150 feet.