Definition
A principle of fluid mechanics stating that pressure applied to a confined fluid is transmitted equally and undiminished in all directions throughout the fluid, and acts at right angles to the surfaces of its container.
Plain English
If you push on a liquid that is sealed inside a container, that push is felt the same way at every point inside, no matter where you push or where you measure.
Context Anchor
Seen in aircraft hydraulic system discussions, especially brakes, landing gear, flaps, and other systems moved by fluid pressure.
Derivation
Named after Blaise Pascal, the 17th-century French scientist who first described the behaviour of pressure in confined fluids. Knowing the name belongs to a person, not a technical word, removes any confusion about what 'Pascal' means here.
Why Pilots Care
Aircraft hydraulic systems depend on this law to transmit and multiply control forces reliably from the cockpit to brakes and flight surfaces.
Analogy
Think of a sealed toothpaste tube. Squeeze it anywhere and the paste comes out the open end -- the squeeze is felt throughout the whole tube, not just where your fingers are.
Grounding Statement
In an aircraft hydraulic system, the fluid is trapped in lines and cylinders, so pressure applied at one point can do work at another point.
Intuition Check
Pascal's law does not mean liquid creates force by itself. It means an applied pressure is carried through an enclosed liquid.
Example Sentence 1
Pascal's Law explains how light pressure on the brake pedal is transmitted through the hydraulic lines to clamp the brakes firmly on the wheels.
Example Sentence 2
Light stick inputs move heavy control surfaces because the hydraulic system follows Pascal's Law to multiply force.