[XKCD] Pascal's Law

When they added hydraulic pumps to LEGO was when shit really got real.
- Pneumatics. But I agree.

https://en.m.wikipedia.org/wiki/Ruina_montium
- Still confused. They're sinking shafts at an angle into rock, filling with water, the pressure towards the bottom breaks the rock.
  And then? How is the water drained, the shaft re- stabilised, etc
  
  The water isn't drained. You sink the shaft past what you need to extract. Restabilization is why slave lives were so cheap. This was gulag work. Shafts would collapse all the time. It's not a modern mining operation.

You can loosely think of hydraulics like pulleys, whatever ratio of input to output power you create is accompanied by a reduction in distance moved.
So a weight of 1kg on an area of 1sqm could balance a weight of 10kg on an area of 10sqm, but moving the 1kg would only generate 1m of travel for every 10m of movement applied.
If you try and displace 1sqm by 10m, you are displacing 10 cubic metres. If you use that displacement to move an area 10x the size, it need only move 1/10 of the distance i.e. 1 metre
You need to keep adding weight (force) to achieve the movement. The initial weight will only balance the system.
I assume that the comic is about breaking apart the mountain, you don't have to move far at all to achieve destruction. You also need a watertight system.
- Pully system is pretty weird, but I like levers for my intuition. You can directly see smaller part moving smaller distance but with greater force. Also you always experience it when opening doors by pusing various parts
- I like to explain it using the word "spend".
  Like all levers you spend one quantity to get another. Usually distance/force; you spend distance to get force, or you spend force to get distance.
  
  Work is the product of force and distance traveled.
  
  This is a way better and simpler explanation of the general principle. Thanks
- Yes, but it's way easier to add more fluid to an hydraulic system than it is to add travel distance to a pulley or size to a lever. So we kinda break that rule by adding a little bit of movement again and again.

So this is how hydraulic thingies work. I never bothered looking it up.
- I don't know about you, but I was just waiting on the relevant xkcd to provide the education. Why seek when you can have it come to you?

Hydraulic pressure is pretty crazy, power densities can get insane.
- I mean, a human being can lift a car with very little effort.
  It's also why most earth moving equipment is hydraulic.
  
  It doesn’t take less effort, it is just stretched out over an amount of time necessary for your body to keep up. And yes I know I sound like an pedantic jerk, but I work on hydraulic systems every day and know how they work 😅
  
  The only really limiting factor is the pressure holding ability of your cylinder wall and the sealing surfaces.
  Hey you wanna lift 6000T, hydraulics will do it!