Physics of Fluids

Fluids

Substances that can flow and take the shape of their containers, including liquids and gases such as water and air.

Density

A fundamental property equal to the mass divided by the unit volume

density = m/V

Density formula

kg/m³

SI unit of Density

Pressure

This is how much force is applied per unit area

Pressure

Force applied per unit area

p = F/A

Pressure formula

Pa or N/m²

Pressure SI units

Atmospheric pressure

The pressure exerted on all surfaces by the air in the Earth’s atmosphere

Gauge Pressure

The pressure of a fluid relative to the atmospheric pressure.

Absolute pressure

The pressure of a fluid relative to the zero pressure experienced in a vacuum.

Hydrostatic pressure

The pressure exerted by a static fluid as a result of the force of gravity acting on it.

Pascal’s Principle

States that a pressure exerted on a confined, incompressible fluid is transmitted equally to all points within the fluid and its container.

Buoyant Force

The upward force that acts on objects in a fluid (either fully or partially), which is equivalent to the weight of the fluid that the object displaces

Archimedes' Principle

States that the buoyant force on an object submerged in a fluid is equivalent to the weight of the fluid that the object displaces.

Bernoulli’s Principle

As the speed (velocity) of a moving fluid increases, the internal pressure of that fluid decreases (and vice versa)

p + 1/2pv²+(rho)gh=constant

Bernoulli’s principle formula

velocity

v

acceleration

g

elevation

h

Fb > Weight

What happens in Positive buoyancy

Fb = Weight

What happens in neutral buoyancy

Fb < Weight

What happens in negative buoyancy

fluid density

rho