pulley

A pulley is a wheel with a grooved rim that carries a rope, cable or belt. A single fixed pulley bolted overhead changes the direction of your pull — you pull down and the load rises — but it does not reduce the force you must apply at all.

A movable pulley, one that rises with the load, does reduce it: the load is shared between two parts of the rope, so the effort needed is roughly halved, though you must pull twice as much rope to raise the load the same distance. Combine fixed and movable wheels into a block and tackle and the reduction grows with the number of rope sections supporting the load. Less force always costs more distance.

That trade is what the questions test: a pulley lets you exchange distance for force, so lifting something heavy a short way becomes easier. Pulleys turn up in cranes, flagpoles, window blinds and engine hoists.