- Engineering : The profession in which a knowledge of the mathematical and natural sciences gained by study, experience and practice is applied with judgment to develop ways to economically use the materials and forces of nature for the benefit of mankind.
- Physics : The study of forces and energies in space and time.
- Chemical engineering : The field of engineering that deals with industrial and natural processes involving the chemical, physical or biological transformation of matter or energy into forms useful for mankind, economically and safely without compromising the environment
- Civil engineering : A broad field of engineering dealing with the design, construction, and maintenance of fixed structures, including roads, buildings, airports, tunnels, dams, bridges, and water supply and sewage systems.
- Mechanical engineering : The branch of engineering concerned with the utilisation of the basic laws of mathematics, thermodynamics, fluid dynamics, and system dynamics in order to create unique solutions to physical problems.
- Pressure : A ratio equal to the force applied perpendicular to the surface of the area divided by that area (force/area).
- Atmosphere (unit) : A unit of pressure measurement (symbol: atm) defined as 101,325 pascal.
- Atmospheric pressure : The ambient air pressure at any given point in Earth's atmosphere.
- Bar (unit) : A unit of pressure measurement (symbol: bar) defined as 100,000 Pascals.
- Evangelista Torricelli : Add brief definition or description
- International System of Units : Metric unit system based on the metre, kilogram, second, ampere, kelvin, mole and candela.
- Kilogram : The kilogram is the basic unit of mass in the International System of Units (SI, metric system).
- Kilogram-force per square centimeter : The kilogram-force per square centimeter (symbol: kgf/cm2 or often just kg/cm2) is a unit of pressure defined as the force exerted by one kilogram-force on one square centimeter.
- Mercury (element) : A chemical element, having the chemical symbol Hg, and atomic number (the number of protons) 80.
- Pascal (unit) : The SI unit of pressure; the force of one newton acting uniformly over an area of one square metre.
- Pound per square inch : A unit of pressure in the U.S. customary units and defined as the pressure exerted by a force of one pound-force applied to an area of one square inch.
- Pound (mass) : A measurement unit of mass used in the United States customary, Imperial, and other systems of measurement.
- Reference conditions of gas temperature and pressure : The temperature and pressure conditions that define the density of a gas and serve to document a stated gas volume.
- Thermodynamics : The statistical description of the properties of molecular systems
- U.S. customary units : The units of measurement that are currently used in the United States.