pascal's law?
Pascal’s law (Pascal’s principle) says that any change in pressure applied to a confined, incompressible fluid at rest is transmitted equally and undiminished in all directions throughout the fluid and to the walls of its container.
Core idea
In simple terms, if you squeeze a trapped fluid at one point, the extra pressure appears everywhere inside that fluid, not just where you pushed. The force from this pressure always acts at right angles to any surface in contact with the fluid.
Mathematically, pressure is P=F/AP=F/AP=F/A, where FFF is force and AAA is area. Pascal’s law means the added pressure ΔP\Delta PΔP is the same at all points in the fluid: ΔP1=ΔP2=…\Delta P_1=\Delta P_2=\dots ΔP1=ΔP2=….
Everyday examples
- Hydraulic jack: A small force on a small piston produces a large force on a larger piston because the same pressure acts over a bigger area.
- Car brakes: Pressing the brake pedal increases pressure in brake fluid, which is transmitted to pistons at each wheel, so all brakes engage together.
- Hydraulic press: Used in workshops to compress, lift, or shape materials by amplifying force via different piston areas.
In each case, the key trick is using equal pressure but different areas so that F2=P×A2F_2=P\times A_2F2=P×A2 can be much larger than the input force F1F_1F1.
Why it works (intuition)
For a fluid at rest, if pressure were higher in one region than a neighboring region at the same depth, the fluid would start to flow, contradicting the “at rest” condition. So the pressure must balance out, giving the same added pressure everywhere inside a connected, confined fluid.
