Why are pulleys so cool?

Well, who said pulleys were cool in the first place? Pulleys have been around for at least 17 centuries or even more (See History of pulley). Today we still use them in many different applications such as ropes in ships, belts in our cars, cranes, and so on. In fact I thought about writing about pulleys the other day when I was at the gym and saw that just about all of the weight machines use some sort of a pulley system. If the fact that pulleys have been around for centruies and are still used today doesn’t make them cool, then I dont know what else would!
There are several reasons why pulleys are so useful even in today’s world. One of them is that they can transmit rotational motion. For example, the pulleys in our car translate the rotational motion of the engine to power the cooling fan, the alternator, the compressor for the ac, and other devices. However, I would like to discuss and illustrate 2 other reasons.
1) One advantage to pulleys that we take for granted is that they allow us to change the direction of a force. For example we can use a pulley to lift a weight. In the picture below we see that by using a pulley we can lift a weight up by pulling down. Even though this seems simple, think about it: you are pulling down to lift something up (isn’t up and down opposite directions?)
2) Another benefit that we get from the use of pulleys is mechanical advantage. If you use pulleys in the right configuration you can reduce the amount of force you need to perform a take. For example let’s take the same case of lifting a weight but this time lets use two pulleys as illustrated in the picture below.
The idea here is that the tension in a string is always the same, therefore by using 2 pulleys in the right configuration you can reduce the force required to lift the weight by 2. This is what we call mechanical advantage. Let’s face it we all love to have an advantage against our opponent right?
If you do it right, you can use 3 pulleys and cut the required force by 3 or use 4 pulleys and cut the required force by 4 and so on. The only thing that changes is that if you use 1 pulley and pull the rope 1 meter, the weight will be lifted 1 meter. However if you use 2 pulleys and pull the rope 1 meter, the weight will be lifted ½ meter and son of for 3, 4,…, number of pulleys.

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