General Physics 2: Fluid Mechanics and Fluid Statics

Comprehensive vocabulary flashcards covering the physical properties of fluids, fluid statics, Pascal's Principle, hydraulic systems, and Archimedes' Principle.

Fluid

Any substance that can flow and take the shape of its container, encompassing both liquids and gases.

Liquid

A state of fluid that possesses a definite volume and takes the shape of its container, such as water, oil, or milk.

Gas

A state of fluid that has no definite shape or volume and expands to fill any container, such as air, oxygen, or helium.

Fluid Density

The amount of mass contained in a given volume of a substance, calculated as $\rho = \frac{m}{V}$ and measured in kilograms per cubic meter ($\text{kg/m}^3$).

Fluid Viscosity

A fluid's internal resistance to flow, characterizing how strongly adjacent fluid layers resist sliding motion past one another.

Effect of Temperature on Fluid Viscosity

In liquids, increasing temperature generally decreases viscosity because molecules move past each other more easily; in gases, increasing temperature increases viscosity because faster-moving molecules transfer momentum between layers more effectively.

Newtonian Fluids

Fluids whose viscosity remains approximately constant at a given temperature and pressure, regardless of the applied shear rate (such as water, air, and light oils).

Non-Newtonian Fluids

Fluids that do not maintain a constant relationship between shear stress and shear rate, resulting in apparent viscosity changes when stirred, shaken, squeezed, or deformed (such as ketchup, toothpaste, and cornstarch mixed with water).

Fluid Pressure

The magnitude of the force exerted perpendicular to a surface per unit area, defined by the formula $P = \frac{F}{A}$ and measured in pascals ($\text{Pa}$), where $1\,\text{Pa} = 1\,\text{N/m}^2$.

Hydrostatic Pressure Formula

$\Delta P = \rho g h$, which shows that the pressure in a static fluid increases with depth due to the weight of the fluid column above.

Surface Tension

The property of a liquid's surface that causes it to behave like a stretched elastic membrane, caused by an imbalance of cohesive attractive forces acting on molecules at the boundary to minimize surface area.

Fluid Compressibility

A measure of how much a substance's volume decreases under applied pressure; liquids exhibit very low compressibility due to closely spaced molecules, whereas gases are highly compressible.

Hydraulic System

A mechanism that utilizes an enclosed liquid (typically oil or water) to transmit applied force undiminished from one piston to another according to Pascal's Principle.

Pascal's Principle

The law of fluid mechanics stating that pressure applied to an enclosed fluid is transmitted equally and undiminished throughout the fluid and to the walls of its container.

Blaise Pascal

The French mathematician, physicist, inventor, and philosopher (1623–1662) who described fluid pressure transmission in his 1653 work Treatise on the Equilibrium of Liquids (Traité de l’équilibre des liqueurs).

Input Piston

The smaller-area piston in a hydraulic system where an external force ($F_1$) is applied to generate pressure in the enclosed fluid.

Output Piston

The larger-area piston in a hydraulic system that receives the transmitted fluid pressure and delivers the resulting multiplied output force ($F_2$) to lift or move a load.

Hydraulic Fluid

The confined working liquid inside a hydraulic system's cylinders and connecting tubing that transmits pressure from the input piston to the output piston.

Hydraulic Lift (Pascal's Law)

A dual-piston system where pressure applied at a small piston ($A_1$) is transmitted through connected tubing to generate a larger force at a large piston ($A_2$), expressed by $\frac{F_1}{A_1} = \frac{F_2}{A_2}$.

Cross-Sectional Area (Hydraulics)

The surface area of a piston face that makes contact with and pushes against the enclosed hydraulic liquid.

Force Multiplication in Hydraulic Systems

The principle where increasing the ratio of output piston area to input piston area ($\frac{A_2}{A_1}$) produces a proportional increase in the output force relative to the input force: $F_2 = F_1 \frac{A_2}{A_1}$.

Archimedes' Principle

The principle stating that an object submerged or floating in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the object.

Buoyant Force

The upward vertical force exerted by a fluid on an immersed or floating body, determining whether the object floats or sinks based on its balance with the object's downward gravitational weight.