Fluid mechanics: pressure, buoyancy and flow — how liquids and gases behave at rest and in motion, from Archimedes’ principle to Bernoulli’s equation.
Fluid Mechanics is the physics of liquids and gases, at rest and in motion — pressure, buoyancy, flow rate and viscosity, and the reason a heavy steel ship floats while a small stone sinks.
| Relationship | Equation | What it tells you |
|---|---|---|
| Pressure | P = F / A | Force spread over a contact area |
| Fluid pressure | P = ρ·g·h | Pressure at depth h in a fluid |
| Archimedes' principle | F = ρ·V·g | Upthrust equals the weight of fluid displaced |
| Continuity | A1·v1 = A2·v2 | Volume flow rate is conserved along a pipe |
| Bernoulli's equation | P + ½·ρ·v² + ρ·g·h = constant | Energy per unit volume along a streamline |
| Pascal's law | F2 = F1 · (A2/A1) | Force multiplication in a hydraulic press |
