Physics: Pressure and Fluid Principles

Vocabulary-style practice flashcards covering liquid pressure, atmospheric pressure, gas pressure, Pascal's Principle, Archimedes' Principle, and Bernoulli's Principle based on the lecture notes.

Liquid Pressure Formula ($P = h\rho g$)

The formula where $P$ is liquid pressure in $Pa$, $h$ is depth in $m$, $\rho$ is density in $kg\,m^{-3}$, and $g$ is gravitational acceleration ($9.81\,m/s^2$).

True Pressure

The sum of the liquid pressure and the atmospheric pressure ($\text{True Pressure} = \text{Liquid Pressure} + \text{Atmospheric Pressure}$).

Atmospheric Pressure

Pressure caused by the weight of the air layers acting on the Earth's surface.

Mercury Barometer

An instrument used to measure atmospheric pressure where the height of the mercury column at sea level is $760\,mm$.

Fortin Barometer

A large, high-accuracy ($\pm 0.1\,mmHg$) barometer based on changes in the height of a mercury column, used to measure atmospheric pressure.

Aneroid Barometer

A small, portable barometer that gives direct readings based on the volume change of a partial vacuum metal box, with an accuracy of approximately $\pm 1\,mmHg$.

Manometer

A device used to determine gas pressure by measuring the difference in liquid levels ($P_{gas} = P_{atm} + P_L$) when connected to a gas supply.

Pascal's Principle

The principle stating that pressure applied to an enclosed fluid is transmitted uniformly in all directions throughout the fluid.

Hydraulic System

A system that utilizes Pascal's Principle to transmit pressure through a liquid, often acting as a force multiplier ($\frac{F_1}{A_1} = \frac{F_2}{A_2}$).

Multiplication Factor ($A_2/A_1$)

The ratio in a hydraulic system of the output piston area to the input piston area which determines the force multiplication.

Archimedes' Principle

The principle stating that an object partially or fully immersed in a fluid experiences a buoyant force equal to the weight of the fluid displaced.

Buoyant Force ($F_B$)

The upward force resulting from the pressure difference between the upper and lower surfaces of an immersed object, calculated as $F_B = \rho Vg$, where $V$ is the volume of displaced liquid.

Apparent Weight

The resulting weight of an object in a fluid, calculated as the difference between the actual weight and the buoyant force ($\text{Actual Weight} - \text{Buoyant Force}$).

Hydrometer

An instrument used to measure liquid density based on Archimedes' Principle; it sinks deeper in less dense liquids to displace more volume.

Ballast Tank

Components of a submarine that are filled with or emptied of water to control the submarine's weight and allow it to dive or surface.

Bernoulli's Principle

The principle stating that as the velocity of a moving fluid increases, the pressure within the fluid decreases.

Venturi Tube

A tube used to demonstrate Bernoulli's Principle where smaller cross-sections cause higher fluid velocity and lower pressure.

Lift Force (Aerofoil)

A force produced in aircraft wings because higher-velocity air on the upper surface creates a low-pressure area, while lower-velocity air beneath creates high pressure.

Downforce (Racing Car)

A force generated on racing cars where air flows at a higher velocity underneath the car, creating lower pressure below and higher pressure above to increase stability.

Siphon

An application of liquid pressure where atmospheric pressure pushes water into a tube to move it to a lower point.