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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Glossary of physics | 11/13 | https://en.wikipedia.org/wiki/Glossary_of_physics | reference | science, encyclopedia | 2026-05-05T07:51:11.278375+00:00 | kb-cron |
quark An elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei.
quasiparticle
== R ==
radiant energy
radiation
radioactive decay
radionuclide Also radioactive nuclide, radioisotope, or radioactive isotope. Any nuclide possessing excess nuclear energy to the point that it is unstable. Such excess energy is emitted through any of several processes of radioactive decay, resulting in a stable nuclide or sometimes another unstable radionuclide which can then undergo further decay. Certain radionuclides occur naturally; many others can be produced artificially in nuclear reactors, cyclotrons, particle accelerators, or radionuclide generators.
radius of curvature
redshift A phenomenon which occurs when light seen coming from an object that is moving away from the observer is proportionally increased in wavelength or "shifted" to the red end of the visible light spectrum.
refraction The change in direction of a wave as it passes from one transmission medium to another or as a result of a gradual change in the medium. Though most commonly used in the context of refraction of light, other waves such as sound waves and fluid waves also experience refraction.
refractive index
relative atomic mass
relativistic mechanics
relativity
rest frame
rigid body An idealization of a solid body in which deformation is neglected. In other words, the distance between any two given points of a rigid body remains constant in time regardless of the external forces exerted on it. Even though such an object cannot physically exist due to relativity, objects can normally be assumed to be perfectly rigid if they are not moving near the speed of light.
rotational energy Also angular kinetic energy. The kinetic energy due to the rotation of an object, which forms part of its total kinetic energy.
rotational speed Also speed of revolution. The number of complete rotations or revolutions a rotating body makes per unit time.
Rydberg formula A formula used in atomic physics to describe the wavelengths of spectral lines of many chemical elements.
== S ==
scalar Any simple physical quantity that can be described by a single number (as opposed to vectors, tensors, etc., which are described by several numbers such as magnitude and direction) and is unchanged by coordinate system rotations or translations (in Newtonian mechanics) or by Lorentz transformations or central-time translations (in relativity).
scattering The general physical process by which some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more localised non-uniformities in the medium through which they pass.
science A systematic enterprise that builds and organises knowledge in the form of testable explanations and predictions about the universe.
screw A mechanism that converts rotational motion to linear motion, and a torque (rotational force) to a linear force; one of six classical simple machines.
second law of thermodynamics
Seebeck effect
series circuit
shadow matter
shear modulus Also modulus of rigidity.
shear strength
shear stress
shortwave radiation (SW) Radiant energy of the electromagnetic spectrum with wavelengths in the visible, near-ultraviolet, and near-infrared spectra, the broadest definition of which includes all radiation with a wavelength between 0.1 μm and 5.0 μm.
Schrödinger equation A mathematical equation which describes the time evolution of wave functions in quantum mechanics.
simple harmonic motion
simple machine A mechanical device that changes the direction or magnitude of a force. In general, a set of six classical simple machines identified by Renaissance scientists drawing from Greek texts on technology are collectively defined as the simplest mechanisms that can provide mechanical advantage (also called leverage).
siphon A tube in an inverted U shape that causes a liquid to flow uphill without pumps, powered by the fall of the liquid as it flows down the tube under the pull of gravity. The term may also more generally refer to a wide variety of devices involving the flow of liquids through tubes.
Snell's law
solar cell
solid
solid mechanics
solid-state physics
solubility The tendency of a solid, liquid, or gaseous chemical substance (called a solute) to dissolve in another solid, liquid, or gaseous substance (called a solvent) to form a homogeneous solution of the solute in the solvent. The solubility of a solute fundamentally depends on the specific solvent as well as on temperature and pressure.
sonoluminescence
sound A mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas and composed of frequencies within the range of human hearing.
special relativity
specific activity
speed
speed of light (
c
{\displaystyle c}
) A fundamental universal physical constant defined as exactly 299,792,458 metres per second, a figure that is exact because the length of the metre is defined from this constant and the international standard for time. When not otherwise qualified, the term "speed of light" usually refers to the speed of light in vacuum, as opposed to the speed of light through some physical medium.
speed of sound
spherical aberration
spin quantum number
stable isotope ratio The relative abundances of the atomically stable isotopes of a given element as they occur in nature or in a particular experimental context.
stable nuclide Any nuclide that is not radioactive and does not spontaneously undergo radioactive decay, as opposed to a radionuclide. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes.
standard atomic weight
Standard Model The theory of particle physics which describes three of the four known fundamental forces (the electromagnetic force, the weak force, and the strong force, but not the gravitational force) and classifies all known elementary particles.
standing wave
state of matter
statics The branch of mechanics concerned with the analysis of loads (force and torque, or "moment") on physical systems in static equilibrium, that is, in a state where the relative positions of subsystems do not vary over time, or where components and structures are at a constant velocity.
statistical mechanics