What is the difference between a fixed pulley and a moving pulley in a rescue system?

• A. A fixed pulley increases speed; a moving pulley decreases speed.
• B. A fixed pulley increases friction.
• C. A fixed pulley changes direction of force; a moving pulley provides mechanical advantage by reducing the effort needed to lift the load.
• D. Both serve identical functions.

Answer: (C)

In rope rescue, a fixed pulley and a moving pulley serve different roles with force and motion. A fixed pulley is attached to a solid anchor and simply redirects the rope, so the effort you apply does not change in magnitude (aside from friction) but you can pull in a more convenient direction. A moving pulley is attached to the load, and it creates multiple rope segments supporting the load, which divides the force you must apply, giving a mechanical advantage. In an ideal 2:1 moving-pulley setup, you’d lift with about half the load, though you must pull in twice as much rope and the load rises only half as fast as you pull. This distinction is why the correct description is that the fixed pulley changes direction, while the moving pulley provides mechanical advantage by reducing the effort needed to lift the load.