Flagpoles use pulleys, too. The pulley at the top stays in place. It’s called a fixed pulley. A fixed pulley can lift something light. But what if the load is heavy? Add a second pulley below the fixed one! The second pulley will double your force.
Count the pulleys in the drawing below. The number tells you how many times those pulleys increase the force.
A fixed pulley changes the direction of force.
As you add more pulleys, you pull the rope a greater distance. Yet, you use less force to move the load.
More pulleys means that less effort is needed for lifting. Say you had to lift some heavy boxes of books. First, you try a fixed pulley. You take hold of the rope and pull. Four tugs later, the box is on a truck.
For the next box, you add a second pulley. Your force is doubled. You use only half the effort. It’s easier, but it takes eight tugs on the rope.
That’s the trade‑off. The more pulleys you use, the easier it is to pull the rope. You just have to pull it farther.
Pulleys used together make lifting easy.
A block contains several pulleys.