What's the point of using ONLY fixed pulley (not combination) to do work?

Question

My 11-year old cousin's question again...

By using fixed pulley, the only advantage seems to be that it changes the direction of pulling the load from upward manner to downward manner, in correspondence with the direction of gravitational force.

However, there's not much use even with the advantage above because:

(1) the effort applied to move the load has to go a longer distance, showing that the person applying the force will be using more strength, and

(2) it does not make it any significant difference in using less force to lift the load.

Genuine Science experts or teachers, please help to provide a scientically-sound reasoning.

Answer 1

Simple advantage - if I have to lift 150 pounds, say, three feet off the ground to load it onto a pickup truck, I can either bend over and try to break my back or I can let gravity do most of the work by using my own weight to pull down on a rope. The total distance and the amount of work remains the same but I won't need any Tylenol for my back.

Answer 2

It uses less rope.

Answer 3

"the effort applied to move the load has to go a longer distance" wrong.

The distance is the same, the direction is different. And the change in direction is important. Pulling a rope from an overhead pulley, you can use your weight to advantage, ie, pull it down by using your weight.

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Answer 4

faster and cheaper

Answer 5

A good example that demonstrates the power of a single fixed pulley is a flag pole. Think about how a flag pole works. You have a long rope that starts near the base of the pole, goes up the pole around a pulley and comes back down to the other side. You then attach the flag to one end of the rope, and pull the other end down. Pretty simple right? Most flags are very light so why do we use a pulley?

Well consider trying to raise the flag without a pulley? Essentially you would have to  get to the top of the flag pole and attach the flag. This is not only more dangerous, but it takes a lot more work to bring both you and the flag to the top of the pole. Sure you could design some sort of lifting machine, but in the long run this would be more complicated and expensive than a simple pulley.

This simple use of a pulley is used on sail boats to help raise sails. You also see the same use in cranes.