A pulley that is attached to a structure is called a fixed pulley. The wheel of a fixed pulley turns, but the pulley itself does not move. A fixed pulley does not multiply the effort force. The distance you apply the effort is the same as the distance the load moves. A fixed pulley changes the direction of effort. When you pull down on the rope, the load moves up. Pulling down is easier than pulling up because you use your body weight when pulling down. Examples of a fixed pulley can be found at the top of a flagpole. A person standing on the ground can raise the flag to the top of the pole and lower it to the ground again due to the fixed pulley. You raise and lower your window blinds with a fixed pulley.

A moveable pulley is attached to the object you are moving. One end of the rope is attached to a fixed structure overhead. The other end of the rope goes downthrough the pulley attached to the load and then back up to the top. Pulling on the other end of the rope causes the load to move up. The moveable pulley offers a mechanical advantage even though it does not change the direction of effort. The load is supported by rope on both sides of the pulley, which means that half as much effort is needed to lift the load. You must exert effort twice as far as the load moves. The force needed to move an object is less, but the distance through which the force must move is longer.

Try this activity to learn more about pulleys!