Blaise Pascal's name came up when we first discussed the concept of pressure when discussing forces. The pressure exerted by an object is defined as the force per unit of area. What happens if you apply a pressure to a fluid? The answer to that can be found in Pascal's Principle.
Pascal's Principle
A change in pressure at any point in an enclosed fluid at rest is transmitted to all other points of the fluid, including the walls of the container.
There are applications to this principle that are used in the real world. Take for example a hydraulic lift. In a hydraulic lift scenario, a small force is applied to a small area. The pressure on the fluid is then transmitted through the fluid to another part of the lift with a larger area. Because the force per unit area on each side is the same, a small force can be used to support a much larger force through the fluid by changing the area of support.
You can see this principle in action at the car shop when they lift your car, you can see it at the barber shop or salon when they lift you up in your chair by pressing on the pedal, and you can see this when you use a gauge pressure meter.
Question
When you lay an air mattress on the ground, you lay it on top of several pebbles. Why can you not feel the actual pebble when you lay on the mattress?
Because of Pascal's Principle, the pressure exerted by that rock on the bottom of the mattress gets transmitted throughout the entire fluid. You, laying on top, do you not feel a "point" force, but the force spread out over your whole area.
