A fixed (single) pulley provides what mechanical advantage?

Pulley mechanical advantage equals the number of rope segments supporting the load. (1) FIXED PULLEY (single, attached to a fixed point): MA = 1. It changes direction (pulling down to lift up) but does not reduce the force needed. The load and effort move equal distances. Example: a flag-raising pulley. (2) MOVABLE PULLEY (attached to the load itself): MA = 2. Two rope segments support the load, halving the effort needed, but doubling the distance the rope is pulled. (3) COMPOUND PULLEY SYSTEMS (block and tackle): MA = number of supporting rope segments. A 4-pulley system with 4 supporting segments has MA = 4 — one-quarter the force, four times the distance. Trade-off principle (universal in simple machines): mechanical advantage = force multiplied / distance reduced. Force × Distance = Work; ignoring friction, work in = work out. A 4:1 pulley needs 1/4 the force but pulls 4 times the rope. Real-world losses to friction reduce ideal MA. Counting supporting segments: count the rope segments under the movable pulley(s) that actually support the load, not the rope you're pulling on (which is on top). For typical ASVAB problems, draw the system and count.