A rotor current meter is an instrument used to measure the velocity of flowing water in rivers, streams, or other water bodies. It operates on the principle of measuring the rotational speed of a rotor (or impeller) that is set in motion by the flow of water. As water passes over or through the rotor, it causes the rotor to spin, and the speed of this rotation correlates with the velocity of the water.

Salt fingering is a physical oceanographic process that occurs primarily in ocean waters where strong vertical salinity gradients exist, typically in regions where lighter freshwater overlays denser saltwater. It is particularly notable in areas like estuaries and regions affected by river outflows. The process involves the interplay of temperature and salinity, which can cause instability in the water column.

Significant wave height (often abbreviated as Hs) is a measure used in oceanography and meteorology to quantify the height of waves in a body of water. Specifically, it is defined as the average height of the highest one-third of the waves observed over a specific period. This metric provides a useful representation of the wave conditions because it tends to give a more accurate portrayal of the sea state than simply taking the average of all wave heights.

Wind-wave dissipation refers to the process by which energy from wind-generated waves is lost due to various physical mechanisms. When waves are generated by wind, they carry energy across the surface of the water. However, this energy does not remain indefinitely; it dissipates over time and distance due to several factors, including: 1. **Frictional Losses**: As waves move through the water, they encounter friction against the water surface and the seabed, resulting in energy loss.

Wind stress refers to the force exerted by the wind on the surface of a body of water or land. This force arises from the wind’s speed and direction and plays a crucial role in the movement of water bodies, influencing ocean currents, waves, and weather patterns.

The Fiber Volume Ratio (FVR) is a measure used in composite materials science to express the proportion of the volume of fibers to the total volume of the composite material. It is typically used to characterize composite materials that consist of reinforcing fibers embedded in a matrix, such as polymer, metal, or ceramics.

In physics, elasticity refers to the property of a material to deform when a force is applied and then return to its original shape when the force is removed. This behavior is observed in various materials, such as rubber bands, metals, and many other elastic substances. The fundamental concept of elasticity can be defined using Hooke's Law, which states that the strain (deformation) in a solid material is directly proportional to the applied stress (force) within the elastic limit of that material.

Admittance, in electrical engineering, refers to a measure of how easily a circuit or component allows the flow of alternating current (AC) when a voltage is applied. It is the reciprocal of impedance (Z) and is a complex quantity, encompassing both conductance (G) and susceptance (B). Mathematically, admittance (Y) is expressed as: \[ Y = \frac{1}{Z} \] where \( Z \) is the impedance of the circuit.

Electric potential, often referred to as voltage, is a measure of the potential energy per unit charge at a specific point in an electric field. It indicates how much work would be needed to move a positive test charge from a reference point (commonly taken as infinity or a grounded point) to the point in question, without any acceleration.

The bulk modulus, often denoted by the symbol \( K \), is a measure of a material's resistance to uniform compression. It quantifies how incompressible a substance is; the higher the bulk modulus, the less compressible the material. Mathematically, the bulk modulus is defined as the ratio of the change in pressure to the relative change in volume of the material.

In physics, "charge" refers to the property of a particle that determines its electromagnetic interactions. It is a fundamental characteristic of certain subatomic particles, most notably electrons and protons, which exhibit electric charge. There are two types of electric charge: positive and negative. 1. **Positive Charge**: Carried by protons. When two objects with positive charges are brought close to each other, they repel each other. 2. **Negative Charge**: Carried by electrons.

Coercivity is a term commonly used in the field of magnetism and materials science. It refers to the ability of a magnetic material to withstand an external magnetic field without becoming demagnetized. More specifically, coercivity is defined as the intensity of the external magnetic field that must be applied in the opposite direction to reduce the magnetization of a material to zero after it has been magnetized.

In chemistry, cohesion refers to the intermolecular attraction between molecules of the same substance. It is the force that holds molecules together, resulting from various types of intermolecular forces, including hydrogen bonding, van der Waals forces, and dipole-dipole interactions. Cohesion plays a crucial role in determining the physical properties of materials, such as their state (solid, liquid, gas), surface tension, and viscosity.

In physics, the term "cross section" refers to a measure of the probability of an interaction between particles, typically in the context of scattering experiments or nuclear reactions. It is a crucial concept in fields such as high-energy particle physics, nuclear physics, and astrophysics. The concept of cross section can be understood as follows: 1. **Geometric Analogy**: Imagine a beam of particles (like protons or neutrons) being directed at a target (another particle or a nucleus).

Hypervelocity refers to extremely high speeds, typically defined as speeds exceeding 1,000 meters per second (about 3,280 feet per second), or approximately Mach 3, depending on the context. In various fields, hypervelocity has specific implications: 1. **Aerospace and Engineering**: In aerospace engineering, hypervelocity is often associated with the motion of objects re-entering the atmosphere from space, such as spacecraft and meteoroids.

Electron mobility refers to the ability of electrons to move through a material when subjected to an electric field. It is a crucial parameter in understanding the electrical properties of semiconductors and conductors. Mobility is typically denoted by the symbol \( \mu \) and is defined as the proportionality constant between the drift velocity of charge carriers (in this case, electrons) and the electric field applied.

Particle displacement refers to the change in position of a particle from its original location due to various forces or perturbations. In physics, particularly in mechanics and wave theory, it describes how far a particle has moved from its rest position. In a more specific context: 1. **Mechanical Systems:** In the study of vibrations and oscillations, particle displacement is often used to describe how particles in a medium (like a solid or fluid) move as a wave propagates through it.

Helmholtz free energy, denoted as \( A \) or sometimes \( F \), is a thermodynamic potential that measures the useful work obtainable from a thermodynamic system at constant temperature and volume.

ISO/IEC 80000 is a standard that addresses the quantities and units of measurement in various fields of science and technology. It is part of the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) standards series focused on providing a clear, consistent, and international way of dealing with measurements and their units.

Fluid mechanics is a complex field of study that encompasses a wide range of phenomena related to the behavior of fluids (liquids and gases) in motion and at rest. Below is a list of some fundamental equations and principles commonly used in fluid mechanics: ### 1.