In a 3:1 system, if the load moves 50 feet upward, how many feet of rope must be pulled through?

• A. 50
• B. 100
• C. 200
• D. 150

Answer: (D)

In a 3:1 haul system, three segments of rope support the load, so the system moves the load with a mechanical advantage of 3. That means for every 1 unit of load rise, you must pull 3 units of rope. If the load goes up 50 feet, you’ve got to pull 50 × 3 = 150 feet of rope through the system. In real setups, small losses from friction or device inefficiencies can require a bit more rope, but the fundamental rule is that you pull three times the load movement.