2026-08-20 21:54:58: Fluids

physics/Fluids/Fluid and Newton Laws.md

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+[[Fluids]]

physics/Fluids/Internal Structure and Density.md

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+[[Fluids]]
+
+# Summary
+* Fluids are substances with no fixed shape.
+* Density: $p=m/V$
+* Difference between states of matter is how strongly their particles interact.
+* Object floats when density is less than surrounds density.
+* Ideal fluid has no viscosity and is incompressible.
+* Density changes with temperature and pressure.

physics/Fluids/Pressure.md

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+[[Fluids]]
+Pressure is perpendicular force acting on a surface divided by area.
+
+# Summary
+* $P=\frac{F_\perp}{A}$
+* Scalar.
+* Incompressible fluids keep constant density and volume when pressure changes.
+* $P=P_0+pgh$
+* At the fluid surface h is 0.
+* Measured in pascals (1 Pa = N/m^2)
+# Absolute vs Gauge Pressure
+Absolute pressure is total pressure: $P=P_0+pgh$, where $P_0$ is a reference pressure such as atmospheric pressure ($P_{atm}$) and gauge pressures is $pgh$. Positive gauge pressure means above atmospheric, negative means below.