How do simple machines actually work?


I’m a student and last year we were been taught about the different kinds of simple machines like screws, pulleys etc., but it feels like no matter where I look nothing seems explain the “how” behind manipulating force and distance, only that they simply do.

Is there something happening at a microscopic level with the force that allows less energy to be used to do the same work? Maybe this is also a question about the moment of a force? They seem interrelated even though they weren’t taught together.

(Also this is my first ever post on Reddit. I hope I was clear enough!)

In: 3

Let me introduce you to the simplest of the simple machines:

The bucket!

You can’t lift 1 ton of water from the well in one go but you can lift 100 buckets of 10 kg of water each. The energy used to lift the water is the same as lifting a 1ton bucket, the only difference is that YOU CAN lift a 10kg bucket and not a ton one.

If you understand this, you understand every other machine. The bucket job is to allow you to get the job done. Every machine is a tool that divides the work to be done into manageable parts.

A pulley: instead of lifting 1 ton directly for a meter, you pull 100 meters of rope with a 10kg force. Same work, same energy, but pulling 10Kg for 100 meters is far more doable than lifting a ton for one meter directly.

A screw: you get the same ton up a meter, but instead of using rope, you carve a helix in a rod, and every turn of the rod will lift the ton by a fraction. Same work same energy. But it’s a lot more doable to turn a crank than to lift a ton directly.

Levers: like the pulley but using a stick and a fulcrum.

Hydraulic machines like a jack are like levers but because the leverage is done with pistons and oil the whole device is a lot more compact or powerful.

All this mechanism have a thing in common: use brain to change the game into something you can win. It’s changing how the game is played, the result and energy is the same, it’s the “access” to the game that is changed.

Hope this helped, have a great day!