| Term | Definition |
|---|---|
| density | A measure of how much mass is contained in a given volume of a substance, calculated as the ratio of mass to volume. |
| fluid | A substance that can flow and conform to the shape of its container, including liquids and gases. |
| gas | A state of matter with no fixed shape or volume, where atoms and molecules have minimal interactions and move freely. |
| ideal fluid | A theoretical fluid that is incompressible and has no viscosity, used as a model for analyzing fluid behavior. |
| incompressible | A property of a fluid that cannot be reduced in volume by the application of pressure. |
| liquid | A state of matter with a fixed volume but no fixed shape, where atoms and molecules have moderate interactions. |
| mass | The amount of matter in an object, typically measured in kilograms. |
| solid | A state of matter with a fixed shape and fixed volume, where atoms and molecules are tightly bonded. |
| viscosity | A measure of a fluid's resistance to flow, or its internal friction. |
| volume | The amount of space occupied by a substance or object, typically measured in cubic meters or liters. |
| Term | Definition |
|---|---|
| absolute pressure | The total pressure at a given point in a fluid, equal to the sum of a reference pressure and the gauge pressure. |
| atmospheric pressure | The pressure exerted by the weight of the atmosphere, commonly used as a reference pressure (Patm). |
| fluid | A substance that can flow and conform to the shape of its container, including liquids and gases. |
| gauge pressure | The pressure of a fluid measured relative to a reference pressure, typically atmospheric pressure, calculated as the difference between absolute pressure and reference pressure. |
| incompressible fluid | A fluid whose density remains essentially constant during flow, regardless of pressure changes. |
| perpendicular force component | The component of a force that acts at a right angle to a surface. |
| pressure | The magnitude of the perpendicular force component exerted per unit area over a given surface area. |
| reference pressure | A baseline pressure used as a starting point for measuring gauge pressure, such as atmospheric pressure (P0). |
| scalar | A physical quantity that has magnitude only, without direction. |
| Term | Definition |
|---|---|
| buoyant force | The net upward force exerted on an object by a fluid as a result of pressure differences across the object's surface. |
| constituent particles | The individual molecules or atoms that make up a fluid. |
| external forces | Forces applied to a fluid from outside sources that affect its motion and behavior. |
| fluid | A substance that can flow and conform to the shape of its container, including liquids and gases. |
| fluid displaced | The volume of fluid that is pushed aside or occupies the space taken up by a submerged or partially submerged object. |
| fluid velocity | The speed and direction of fluid motion, which changes in response to internal particle interactions and external forces. |
| internal interactions | The forces and interactions between particles within a fluid that contribute to its macroscopic behavior. |
| macroscopic behavior | The large-scale, observable behavior of a fluid as a whole, resulting from the combined effects of internal particle interactions and external forces. |
| Newton's laws | The three fundamental laws of motion that describe how forces affect the motion of objects, including particles within a fluid. |
| weight of fluid displaced | The gravitational force exerted on the volume of fluid that an object displaces, which equals the magnitude of the buoyant force. |
| Term | Definition |
|---|---|
| Bernoulli's equation | A mathematical equation describing the conservation of mechanical energy in fluid flow, relating pressure, gravitational potential energy, and kinetic energy at two points in a fluid. |
| conservation of mechanical energy | The principle that the total mechanical energy of a system remains constant when only conservative forces act on it, or changes by an amount equal to energy transferred into or out of the system. |
| continuity equation | The mathematical relationship stating that the mass flow rate of an incompressible fluid remains constant throughout a tube, expressed as A₁v₁ = A₂v₂. |
| cross-sectional area | The area of a surface perpendicular to the direction of fluid flow through a tube or channel. |
| flow rate | The volume or mass of fluid passing through a cross-sectional area per unit time. |
| fluid flow | The motion of a fluid from one location to another, driven by differences in energy within the fluid-Earth system. |
| gravitational potential energy | The potential energy of a system due to the gravitational interaction between two masses separated by a distance. |
| incompressible fluid | A fluid whose density remains essentially constant during flow, regardless of pressure changes. |
| kinetic energy | The energy possessed by an object due to its motion, equal to one-half the product of its mass and the square of its velocity. |
| mass conservation | The principle that the total mass of a system remains constant over time, with no mass created or destroyed. |
| pressure | The magnitude of the perpendicular force component exerted per unit area over a given surface area. |
| pressure difference | The variation in pressure between two locations that causes a fluid to flow from higher to lower pressure. |
| Torricelli's theorem | A principle stating that the speed of a fluid exiting an opening is related to the vertical distance between the opening and the fluid's surface, derived from conservation of energy. |