Pascal's principle

Statement

Additional pressure applied to a confined fluid is transmitted undiminished to every point of the fluid and the vessel walls — independent of container shape.

Why is it true?

In an incompressible fluid, molecular collisions immediately relay every pressure change — a perfect "broadcast channel".

Combined with force = pressure × area: pushing a small piston with a small force lifts a large piston with a large force — the working principle of every hydraulic machine.

Applications

Hydraulic jacks and car brakes, hydraulic presses, aircraft fly-by-wire controls, hospital bed lifts, central hydraulic systems.

Topics that use this theorem

Related theorems

Step-by-step proofs