English dictionary of Physics

English dictionary of Physics

 English dictionary of Physics

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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A
absolute zero
(cryogenics) the lowest temperature theoretically attainable (at which the kinetic energy of atoms and molecules is minimal); 0 Kelvin or -273.15 centigrade or -459.67 Fahrenheit

absorptivity ; absorption factor
(physics) the property of a body that determines the fraction of the incident radiation or sound flux absorbed or absorbable by the body

accelerate
move faster; "The car accelerated"

acceleration ; quickening ; speedup
the act of accelerating; increasing the speed

acoustics
the study of the physical properties of sound

adhesiveness ; adhesion
the property of sticking together (as of glue and wood) or the joining of surfaces of different composition; "the mutual adhesiveness of cells"; "a heated hydraulic press was required for adhesion"

adiabatic process
(thermodynamics) any process that occurs without gain or loss of heat

alternating current ; AC ; alternating electric current
an electric current that reverses direction sinusoidally; "In the US most household current is AC at 60 cycles per second"

amplitude
(physics) the maximum displacement of a periodic wave

antiferromagnetism
magnetic field creates parallel but opposing spins; varies with temperature

assimilation ; absorption
the social process of absorbing one cultural group into harmony with another

atmosphere
a unit of pressure: the pressure that will support a column of mercury 760 mm high at sea level and 0 degrees centigrade

atom
(physics and chemistry) the smallest component of an element having the chemical properties of the element

attraction
an entertainment that is offered to the public

attraction ; attractive force
the force by which one object attracts another

axis ; axis of rotation
the center around which something rotates


B
balance
a state of equilibrium

balance ; equilibrium ; equipoise
equality of distribution

battery ; electric battery
a device that produces electricity; may have several primary or secondary cells arranged in parallel or series

boiling point ; boil
the temperature at which a liquid boils at sea level; "they brought the water to a boil"

bulk ; volume
the property of something that is great in magnitude; "it is cheaper to buy it in bulk"; "he received a mass of correspondence"; "the volume of exports"


C
calorimetry
measurement of quantities of heat

capacitance ; electrical capacity ; capacity
an electrical phenomenon whereby an electric charge is stored

capacitor ; condenser
an electrical device characterized by its capacity to store an electric charge

capacity ; content
the amount that can be contained; "the gas tank has a capacity of 12 gallons"

causality
the relation between causes and effects

center of mass ; centre of mass
point representing the mean position of the matter in a body

centrifugal
tending to move away from a center; "centrifugal force"

centrifugal force
the outward force on a body moving in a curved path around another body

charge ; electric charge
the quantity of unbalanced electricity in a body (either positive or negative) and construed as an excess or deficiency of electrons; "the battery needed a fresh charge"

chemical ; chemic
relating to or used in chemistry; "chemical engineer"; "chemical balance"

chemical ; chemical substance
material produced by or used in a reaction involving changes in atoms or molecules

chromatic aberration
an optical aberration in which the image has colored fringes

cold ; coldness ; frigidness
the absence of heat; "the coldness made our breath visible"; "come in out of the cold"; "cold is a vasoconstrictor"

collision ; hit
(physics) a brief event in which two or more bodies come together; "the collision of the particles resulted in an exchange of energy and a change of direction"

compass
navigational instrument for finding directions

compressibility
the property of being able to occupy less space

compression
encoding information while reducing the bandwidth or bits required

condensation
the process of changing from a gaseous to a liquid or solid state

conductance
a material's capacity to conduct electricity; measured as the reciprocal of electrical resistance

conduction ; conductivity
the transmission of heat or electricity or sound

conductor
a device designed to transmit electricity, heat, etc.

conservation
(physics) the maintenance of a certain quantities unchanged during chemical reactions or physical transformations

conservation ; preservation
an occurrence of improvement by virtue of preventing loss or injury or other change

conservation of energy ; law of conservation of energy ; first law of thermodynamics
the fundamental principle of physics that the total energy of an isolated system is constant despite internal changes

constant
a number representing a quantity assumed to have a fixed value in a specified mathematical context; "the velocity of light is a constant"

conversion ; changeover
an event that results in a transformation

Coriolis effect
(physics) an effect whereby a body moving in a rotating frame of reference experiences the Coriolis force acting perpendicular to the direction of motion and to the axis of rotation; on Earth the Coriolis effect deflects moving bodies to the right in the northern hemisphere and to the left in the southern hemisphere

cosmology
the metaphysical study of the origin and nature of the universe

cosmology ; cosmogony ; cosmogeny
the branch of astrophysics that studies the origin and evolution and structure of the universe

crystal
a solid formed by the solidification of a chemical and having a highly regular atomic structure

crystal ; crystallization
a rock formed by the solidification of a substance; has regularly repeating internal structure; external plane faces

current ; electric current
a flow of electricity through a conductor; "the current was measured in amperes"


D
decibel ; dB
a logarithmic unit of sound intensity; 10 times the logarithm of the ratio of the sound intensity to some reference intensity

density ; denseness
the amount per unit size

deviation ; deviance
deviate behavior

diamagnetism
phenomenon exhibited by materials like copper or bismuth that become magnetized in a magnetic field with a polarity opposite to the magnetic force; unlike iron they are slightly repelled by a magnet

diffusion
(physics) the process in which there is movement of a substance from an area of high concentration of that substance to an area of lower concentration

diode
a semiconductor that consists of a p-n junction

diopter ; dioptre
a unit of measurement of the refractive power of a lens which is equal to the reciprocal of the focal length measured in meters; used by oculists

dip ; angle of dip ; magnetic dip
(physics) the angle that a magnetic needle makes with the plane of the horizon

dipole
a pair of equal and opposite electric charges or magnetic poles separated by a small distance

direct current ; DC
an electric current that flows in one direction steadily

dispersion ; dispersal
the act of dispersing or diffusing something; "the dispersion of the troops"; "the diffusion of knowledge"

distance
the property created by the space between two objects or points

distortion
an optical phenomenon resulting from the failure of a lens or mirror to produce a good image

drag
pull, as against a resistance; "He dragged the big suitcase behind him"; "These worries were dragging at him"

drag ; retarding force
the phenomenon of resistance to motion through a fluid

drive ; thrust ; driving force
the act of applying force to propel something; "after reaching the desired velocity the drive is cut off"

dynamical system
(physics) a phase space together with a transformation of that space

dynamics ; kinetics
the branch of mechanics concerned with the forces that cause motions of bodies


E
echo
the repetition of a sound resulting from reflection of the sound waves; "she could hear echoes of her own footsteps"

elasticity ; snap
the tendency of a body to return to its original shape after it has been stretched or compressed; "the waistband had lost its snap"

electric field
a field of force surrounding a charged particle

electricity ; electrical energy
energy made available by the flow of electric charge through a conductor; "they built a car that runs on electricity"

electromagnet
a temporary magnet made by coiling wire around an iron core; when current flows in the coil the iron becomes a magnet

electromagnetic
pertaining to or exhibiting magnetism produced by electric charge in motion; "electromagnetic energy"

electromagnetic radiation
radiation consisting of waves of energy associated with electric and magnetic fields resulting from the acceleration of an electric charge

electromagnetic spectrum
the entire frequency range of electromagnetic waves

electromagnetism
magnetism produced by an electric current; "electromagnetism was discovered when it was observed that a copper wire carrying an electric current can magnetize pieces of iron or steel near it"

electron ; negatron
an elementary particle with negative charge

electronics
the branch of physics that deals with the emission and effects of electrons and with the use of electronic devices

electrostatic ; static
concerned with or producing or caused by static electricity; "an electrostatic generator produces high-voltage static electricity"

electrostatics
the branch of physics that deals with static electricity

element
an abstract part of something; "jealousy was a component of his character"; "two constituents of a musical composition are melody and harmony"; "the grammatical elements of a sentence"; "a key factor in her success"; "humor: an effective ingredient of a speech"

elementary particle ; fundamental particle
(physics) a particle that is less complex than an atom; regarded as constituents of all matter

emission ; emanation
the act of emitting; causing to flow forth

energy ; free energy
(physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs; "energy can take a wide variety of forms"

enthalpy
(thermodynamics) a thermodynamic quantity equal to the internal energy of a system plus the product of its volume and pressure; "enthalpy is the amount of energy in a system capable of doing mechanical work"

entropy
(communication theory) a numerical measure of the uncertainty of an outcome; "the signal contained thousands of bits of information"

equilibrium
a stable situation in which forces cancel one another

event ; case
a special set of circumstances; "in that event, the first possibility is excluded"; "it may rain in which case the picnic will be canceled"

expansion ; enlargement
the act of increasing (something) in size or volume or quantity or scope

experiment ; experimentation
the act of conducting a controlled test or investigation


F
ferrimagnetism
a phenomenon in ferrites where there can be incomplete cancellation of antiferromagnetic arranged spins giving a net magnetic moment

ferromagnetism
phenomenon exhibited by materials like iron (nickel or cobalt) that become magnetized in a magnetic field and retain their magnetism when the field is removed

filter ; filtrate
remove by passing through a filter; "filter out the impurities"

firm ; solid
not soft or yielding to pressure; "a firm mattress"; "the snow was firm underfoot"; "solid ground"

flow ; flowing
the motion characteristic of fluids (liquids or gases)

flow ; flux
move or progress freely as if in a stream; "The crowd flowed out of the stadium"

fluid
a substance that is fluid at room temperature and pressure

fluid mechanics ; hydraulics
study of the mechanics of fluids

freeze ; freezing
the withdrawal of heat to change something from a liquid to a solid

freezing point ; melting point
the temperature below which a liquid turns into a solid

frequency ; relative frequency
the ratio of the number of observations in a statistical category to the total number of observations

friction ; rubbing
the resistance encountered when one body is moved in contact with another


G
gas ; gaseous state
the state of matter distinguished from the solid and liquid states by: relatively low density and viscosity; relatively great expansion and contraction with changes in pressure and temperature; the ability to diffuse readily; and the spontaneous tendency to become distributed uniformly throughout any container

gas constant ; universal gas constant ; R
(physics) the universal constant in the gas equation: pressure times volume = R times temperature; equal to 8.3143 joules per kelvin per mole

geophysics ; geophysical science
geology that uses physical principles to study properties of the earth

gravitational constant ; universal gravitational constant ; constant of gravitation
(physics) the universal constant relating force to mass and distance in Newton's law of gravitation

gravity ; gravitation
(physics) the force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface; "the more remote the body the less the gravity"; "the gravitation between two bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them"; "gravitation cannot be held responsible for people falling in love"--Albert Einstein


H
half life ; half-life
the time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate)

heat ; high temperature
the presence of heat

heat ; warmth
the sensation caused by heat energy

height ; tallness
the vertical dimension of extension; distance from the base of something to the top

hertz
the unit of frequency; one hertz has a periodic interval of one second

hypothesis
a tentative insight into the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena; "a scientific hypothesis that survives experimental testing becomes a scientific theory"; "he proposed a fresh theory of alkalis that later was accepted in chemical practices"


I
ideal gas ; perfect gas
a hypothetical gas with molecules of negligible size that exert no intermolecular forces

ignite ; light
cause to start burning; subject to fire or great heat; "Great heat can ignite almost any dry matter"; "Light a cigarette"

imbalance
a lack of balance or state of disequilibrium; "a hormonal imbalance"

impact
the striking of one body against another

impedance ; resistance ; resistivity
a material's opposition to the flow of electric current; measured in ohms

implosion
a sudden inward collapse; "the implosion of a light bulb"

induction ; inductance
an electrical phenomenon whereby an electromotive force (EMF) is generated in a closed circuit by a change in the flow of current

inductor ; inductance
an electrical device (typically a conducting coil) that introduces inductance into a circuit

inertia
(physics) the tendency of a body to maintain its state of rest or uniform motion unless acted upon by an external force

inertia
a disposition to remain inactive or inert; "he had to overcome his inertia and get back to work"

instability ; unstableness
the quality or attribute of being unstable and irresolute

insulator ; dielectric
a material such as glass or porcelain with negligible electrical or thermal conductivity

interaction
a mutual or reciprocal action; interacting

interaction ; fundamental interaction
(physics) the transfer of energy between elementary particles or between an elementary particle and a field or between fields; mediated by gauge bosons

interference
the act of hindering or obstructing or impeding

inverse ; opposite
something inverted in sequence or character or effect; "when the direct approach failed he tried the inverse"

inverse ; reverse
reversed (turned backward) in order or nature or effect

invisibility ; invisibleness
the quality of not being perceivable by the eye

invisible ; unseeable
impossible or nearly impossible to see; imperceptible by the eye; "the invisible man"; "invisible rays"; "an invisible hinge"; "invisible mending"

ion
a particle that is electrically charged (positive or negative); an atom or molecule or group that has lost or gained one or more electrons

isotope
one of two or more atoms with the same atomic number but with different numbers of neutrons

isotropy ; symmetry
(physics) the property of being isotropic; having the same value when measured in different directions


J
joule
a unit of electrical energy equal to the work done when a current of one ampere passes through a resistance of one ohm for one second


K
kinematics
the branch of mechanics concerned with motion without reference to force or mass

kinetic energy ; K.E.
the mechanical energy that a body has by virtue of its motion


L
laser ; optical maser
an acronym for light amplification by stimulated emission of radiation; an optical device that produces an intense monochromatic beam of coherent light

latent heat ; heat of transformation
heat absorbed or radiated during a change of phase at a constant temperature and pressure

length
the linear extent in space from one end to the other; the longest dimension of something that is fixed in place; "the length of the table was 5 feet"

level ; spirit level
indicator that establishes the horizontal when a bubble is centered in a tube of liquid

light
(physics) electromagnetic radiation that can produce a visual sensation; "the light was filtered through a soft glass window"

light
of comparatively little physical weight or density; "a light load"; "magnesium is a light metal--having a specific gravity of 1.74 at 20 degrees C"

light ; illume ; illuminate
make lighter or brighter; "This lamp lightens the room a bit"

liquid
a substance that is liquid at room temperature and pressure

liquid
existing as or having characteristics of a liquid; especially tending to flow; "water and milk and blood are liquid substances"

liter ; litre
a metric unit of capacity, formerly defined as the volume of one kilogram of pure water under standard conditions; now equal to 1,000 cubic centimeters (or approximately 1.75 pints)

lumen ; lm
a unit of luminous flux equal to the amount of light given out through a solid angle of 1 steradian by a point source of 1 candela intensity radiating uniformly in all directions

luminosity ; luminance
the quality of being luminous; emitting or reflecting light; "its luminosity is measured relative to that of our sun"


M
magnet
(physics) a device that attracts iron and produces a magnetic field

magnetic declination ; magnetic variation ; variation
the angle (at a particular location) between magnetic north and true north

magnetic field
the lines of force surrounding a permanent magnet or a moving charged particle

magnetic monopole
a hypothetical particle with a single magnetic pole instead of the usual two

magnetism
attraction for iron; associated with electric currents as well as magnets; characterized by fields of force

magnetism ; magnetics
the branch of science that studies magnetism

mass
the property of a body that causes it to have weight in a gravitational field

measurement ; measuring ; mensuration
the act or process of assigning numbers to phenomena according to a rule; "the measurements were carefully done"; "his mental measurings proved remarkably accurate"

mechanical
using (or as if using) mechanisms or tools or devices; "a mechanical process"; "his smile was very mechanical"; "a mechanical toy"

mechanics
the branch of physics concerned with the motion of bodies in a frame of reference

medium
a means or instrumentality for storing or communicating information

microscope
magnifier of the image of small objects; "the invention of the microscope led to the discovery of the cell"

mirror
polished surface that forms images by reflecting light

mirror
reflect as if in a mirror; "The smallest pond at night mirrors the firmament above"

mole
the molecular weight of a substance expressed in grams; the basic unit of amount of substance adopted under the Systeme International d'Unites

molecule
(physics and chemistry) the simplest structural unit of an element or compound

moment of inertia
the tendency of a body to resist angular acceleration

momentum
the product of a body's mass and its velocity; "the momentum of the particles was deduced from meteoritic velocities"

movement ; motion
a natural event that involves a change in the position or location of something

movement ; motion ; move
a change of position that does not entail a change of location; "the reflex motion of his eyebrows revealed his surprise"; "movement is a sign of life"; "an impatient move of his hand"; "gastrointestinal motility"

mutant
(biology) an organism that has characteristics resulting from chromosomal alteration


N
natural gas ; gas
a fossil fuel in the gaseous state; used for cooking and heating homes

negative
characterized by or displaying negation or denial or opposition or resistance; having no positive features; "a negative outlook on life"; "a colorless negative personality"; "a negative evaluation"; "a negative reaction to an advertising campaign"

neutron
an elementary particle with 0 charge and mass about equal to a proton; enters into the structure of the atomic nucleus

newton ; N
a unit of force equal to the force that imparts an acceleration of 1 m/sec/sec to a mass of 1 kilogram; equal to 100,000 dynes

nuclear ; atomic
(weapons) deriving destructive energy from the release of atomic energy; "nuclear war"; "nuclear weapons"; "atomic bombs"

nuclear reactor ; reactor
(physics) any of several kinds of apparatus that maintain and control a nuclear reaction for the production of energy or artificial elements

nucleus
the positively charged dense center of an atom

nucleus ; cell nucleus ; karyon
a part of the cell containing DNA and RNA and responsible for growth and reproduction


O
opacity ; opaqueness
the quality of being opaque to a degree; the degree to which something reduces the passage of light

optics
the branch of physics that studies the physical properties of light

order of magnitude ; magnitude
a number assigned to the ratio of two quantities; two quantities are of the same order of magnitude if one is less than 10 times as large as the other; the number of magnitudes that the quantities differ is specified to within a power of 10

oscillation
the process of oscillating between states

outer space ; space
any location outside the Earth's atmosphere; "the astronauts walked in outer space without a tether"; "the first major milestone in space exploration was in 1957, when the USSR's Sputnik 1 orbited the Earth"


P
parallax
the apparent displacement of an object as seen from two different points that are not on a line with the object

paramagnetism
materials like aluminum or platinum become magnetized in a magnetic field but it disappears when the field is removed

particle ; subatomic particle
a body having finite mass and internal structure but negligible dimensions

permeability ; permeableness
the property of something that can be pervaded by a liquid (as by osmosis or diffusion)

phenomenon
any state or process known through the senses rather than by intuition or reasoning

photon
a quantum of electromagnetic radiation; an elementary particle that is its own antiparticle

physics ; natural philosophy
the science of matter and energy and their interactions; "his favorite subject was physics"

place
the post or function properly or customarily occupied or served by another; "can you go in my stead?"; "took his place"; "in lieu of"

plasma
(physical chemistry) a fourth state of matter distinct from solid or liquid or gas and present in stars and fusion reactors; a gas becomes a plasma when it is heated until the atoms lose all their electrons, leaving a highly electrified collection of nuclei and free electrons; "particles in space exist in the form of a plasma"

polarization ; polarisation
the condition of having or giving polarity

potential energy ; P.E.
the mechanical energy that a body has by virtue of its position; stored energy

power
(physics) the rate of doing work; measured in watts (= joules/second)

press ; pressure ; pressing
the act of pressing; the exertion of pressure; "he gave the button a press"; "he used pressure to stop the bleeding"; "at the pressing of a button"

pressure
the force applied to a unit area of surface; measured in pascals (SI unit) or in dynes (cgs unit); "the compressed gas exerts an increased pressure"

pressure
a force that compels; "the public brought pressure to bear on the government"

principle of relativity
(physics) a universal law that states that the laws of mechanics are not affected by a uniform rectilinear motion of the system of coordinates to which they are referred

prism
a polyhedron with two congruent and parallel faces (the bases) and whose lateral faces are parallelograms

prism ; optical prism
optical device having a triangular shape and made of glass or quartz; used to deviate a beam or invert an image

process ; physical process
a sustained phenomenon or one marked by gradual changes through a series of states; "events now in process"; "the process of calcification begins later for boys than for girls"

proportion
the quotient obtained when the magnitude of a part is divided by the magnitude of the whole

proportion ; dimension
magnitude or extent; "a building of vast proportions"

proportional ; relative
properly related in size or degree or other measurable characteristics; usually followed by `to'; "the punishment ought to be proportional to the crime"; "earnings relative to production"

proton
a stable particle with positive charge equal to the negative charge of an electron

pulley
a simple machine consisting of a wheel with a groove in which a rope can run to change the direction or point of application of a force applied to the rope

push ; thrust
the force used in pushing; "the push of the water on the walls of the tank"; "the thrust of the jet engines"

pyroelectricity
generation of an electric charge on certain crystals (such as tourmaline) as a result of a change in temperature


Q
quantitative
expressible as a quantity or relating to or susceptible of measurement; "export wheat without quantitative limitations"; "quantitative analysis determines the amounts and proportions of the chemical constituents of a substance or mixture"

quantity
an adequate or large amount; "he had a quantity of ammunition"

quantum
(physics) the smallest discrete quantity of some physical property that a system can possess (according to quantum theory)

quantum electrodynamics ; QED
a relativistic quantum theory of the electromagnetic interactions of photons and electrons and muons

quantum mechanics
the branch of quantum physics that accounts for matter at the atomic level; an extension of statistical mechanics based on quantum theory (especially the Pauli exclusion principle)

quark
(physics) hypothetical truly fundamental particle in mesons and baryons; there are supposed to be six flavors of quarks (and their antiquarks), which come in pairs; each has an electric charge of +2/3 or -1/3; "quarks have not been observed directly but theoretical predictions based on their existence have been confirmed experimentally"


R
radiation
the act of spreading outward from a central source

radiation ; radioactivity
the spontaneous emission of a stream of particles or electromagnetic rays in nuclear decay

reactance
opposition to the flow of electric current resulting from inductance and capacitance (rather than resistance)

reflection ; reflexion
the phenomenon of a propagating wave (light or sound) being thrown back from a surface

refrigeration ; infrigidation
the process of cooling or freezing (e.g., food) for preservative purposes

resistance
any mechanical force that tends to retard or oppose motion

resistance
the capacity of an organism to defend itself against harmful environmental agents; "these trees are widely planted because of their resistance to salt and smog"

resistance ; opposition
the action of opposing something that you disapprove or disagree with; "he encountered a general feeling of resistance from many citizens"; "despite opposition from the newspapers he went ahead"

resistor ; resistance
an electrical device that resists the flow of electrical current

resolution
(computer science) the number of pixels per square inch on a computer-generated display; the greater the resolution, the better the picture

resonance
a vibration of large amplitude produced by a relatively small vibration near the same frequency of vibration as the natural frequency of the resonating system

rotation ; gyration
a single complete turn (axial or orbital); "the plane made three rotations before it crashed"; "the revolution of the earth about the sun takes one year"

rotation ; rotary motion
the act of rotating as if on an axis; "the rotation of the dancer kept time with the music"


S
saturation
a condition in which a quantity no longer responds to some external influence

scientific
of or relating to the practice of science; "scientific journals"

second law of thermodynamics
a law stating that mechanical work can be derived from a body only when that body interacts with another at a lower temperature; any spontaneous process results in an increase of entropy

seismology
the branch of geology that studies earthquakes

semiconductor ; semiconducting material
a substance as germanium or silicon whose electrical conductivity is intermediate between that of a metal and an insulator; its conductivity increases with temperature and in the presence of impurities

shape ; form
the visual appearance of something or someone; "the delicate cast of his features"

shape ; form
the spatial arrangement of something as distinct from its substance; "geometry is the mathematical science of shape"

size
the physical magnitude of something (how big it is); "a wolf is about the size of a large dog"

smoke ; fume
a cloud of fine particles suspended in a gas

solenoid
a coil of wire around an iron core; becomes a magnet when current passes through the coil

solid
of definite shape and volume; firm; neither liquid nor gaseous; "ice is water in the solid state"

sound
the particular auditory effect produced by a given cause; "the sound of rain on the roof"; "the beautiful sound of music"

sound
give off a certain sound or sounds; "This record sounds scratchy"

sound ; audio
the audible part of a transmitted signal; "they always raise the audio for commercials"

space
an empty area (usually bounded in some way between things); "the architect left space in front of the building"; "they stopped at an open space in the jungle"; "the space between his teeth"

space ; infinite
the unlimited expanse in which everything is located; "they tested his ability to locate objects in space"; "the boundless regions of the infinite"

spectrum
an ordered array of the components of an emission or wave

speed ; velocity
distance travelled per unit time

speed of light
the speed at which light travels in a vacuum; the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per second

static
not in physical motion; "the inertia of an object at rest"

stationary
not capable of being moved; "stationary machinery"

statistical mechanics
the branch of physics that makes theoretical predictions about the behavior of macroscopic systems on the basis of statistical laws governing its component particles

stay ; remain ; rest
stay the same; remain in a certain state; "The dress remained wet after repeated attempts to dry it"; "rest assured"; "stay alone"; "He remained unmoved by her tears"; "The bad weather continued for another week"

steam
water at boiling temperature diffused in the atmosphere

strain
injury to a muscle (often caused by overuse); results in swelling and pain

stream ; current
dominant course (suggestive of running water) of successive events or ideas; "two streams of development run through American history"; "stream of consciousness"; "the flow of thought"; "the current of history"

strength ; force
physical energy or intensity; "he hit with all the force he could muster"; "it was destroyed by the strength of the gale"; "a government has not the vitality and forcefulness of a living man"

stress
(physics) force that produces strain on a physical body; "the intensity of stress is expressed in units of force divided by units of area"

stress
(psychology) a state of mental or emotional strain or suspense; "he suffered from fatigue and emotional tension"; "stress is a vasoconstrictor"

string theory
(particle physics) a theory that postulates that subatomic particles are one-dimensional strings

strong interaction ; strong force ; color force
(physics) the interaction that binds protons and neutrons together in the nuclei of atoms; mediated by gluons

structure
the manner of construction of something and the arrangement of its parts; "artists must study the structure of the human body"; "the structure of the benzene molecule"

sublimation
(chemistry) a change directly from the solid to the gaseous state without becoming liquid

substance
the real physical matter of which a person or thing consists; "DNA is the substance of our genes"

substance
material of a particular kind or constitution; "the immune response recognizes invading substances"

supersymmetry
(physics) a theory that tries to link the four fundamental forces; "according to supersymmetry each force emerged separately during the big bang"

surface
the outer boundary of an artifact or a material layer constituting or resembling such a boundary; "there is a special cleaner for these surfaces"; "the cloth had a pattern of red dots on a white surface"


T
telescope ; scope
a magnifier of images of distant objects

temperature
the degree of hotness or coldness of a body or environment (corresponding to its molecular activity)

tension
the physical condition of being stretched or strained; "it places great tension on the leg muscles"; "he could feel the tenseness of her body"

theoretical ; theoretic
concerned primarily with theories or hypotheses rather than practical considerations; "theoretical science"

thermal
relating to or associated with heat; "thermal movements of molecules"; "thermal capacity"; "thermic energy"; "the caloric effect of sunlight"

thermodynamics
the branch of physics concerned with the conversion of different forms of energy

thermoelectricity
electricity produced by heat (as in a thermocouple)

thermometer
measuring instrument for measuring temperature

third law of thermodynamics
law stating that the entropy of a substance approaches zero as its temperature approaches absolute zero

time ; fourth dimension
the fourth coordinate that is required (along with three spatial dimensions) to specify a physical event

torsion ; torque
a twisting force

trajectory ; flight
the path followed by an object moving through space

transformation ; translation
the act of changing in form or shape or appearance; "a photograph is a translation of a scene onto a two-dimensional surface"

transformation ; transmutation
a qualitative change

transistor
a semiconductor device capable of amplification

transition
a change from one place or state or subject or stage to another


U
uniform ; unvarying
always the same; showing a single form or character in all occurrences; "a street of uniform tall white buildings"

unit ; unit of measurement
any division of quantity accepted as a standard of measurement or exchange; "the dollar is the United States unit of currency"; "a unit of wheat is a bushel"; "change per unit volume"


V
vacuum ; vacuity
the absence of matter

value
the quality (positive or negative) that renders something desirable or valuable; "the Shakespearean Shylock is of dubious value in the modern world"

vapor ; vapour
a visible suspension in the air of particles of some substance

vaporization ; evaporation
the process of becoming a vapor

variable
a symbol (like x or y) that is used in mathematical or logical expressions to represent a variable quantity

variable
liable to or capable of change; "rainfall in the tropics is notoriously variable"; "variable winds"; "variable expenses"

variation
a repetition of a musical theme in which it is modified or embellished

vector
a straight line segment whose length is magnitude and whose orientation in space is direction

viscosity ; viscousness
resistance of a liquid to shear forces (and hence to flow)

volatile
tending to vary often or widely; "volatile stocks"; "volatile emotions"

volt ; V
a unit of potential equal to the potential difference between two points on a conductor carrying a current of 1 ampere when the power dissipated between the two points is 1 watt; equivalent to the potential difference across a resistance of 1 ohm when 1 ampere of current flows through it

voltage
the difference in electrical charge between two points in a circuit expressed in volts

voltage
the rate at which energy is drawn from a source that produces a flow of electricity in a circuit; expressed in volts

volume
the amount of 3-dimensional space occupied by an object; "the gas expanded to twice its original volume"


W
wave ; moving ridge
one of a series of ridges that moves across the surface of a liquid (especially across a large body of water)

wave ; undulation
(physics) a movement up and down or back and forth

wave front ; wavefront
(physics) an imaginary surface joining all points in space that are reached at the same instant by a wave propagating through a medium

wavelength
the distance (measured in the direction of propagation) between two points in the same phase in consecutive cycles of a wave

weak interaction ; weak force
(physics) an interaction between elementary particles involving neutrinos or antineutrinos that is responsible for certain kinds of radioactive decay; mediated by intermediate vector bosons

weight
the vertical force exerted by a mass as a result of gravity

weight unit ; weight
a unit used to measure weight; "he placed two weights in the scale pan"

whole ; unit
an assemblage of parts that is regarded as a single entity; "how big is that part compared to the whole?"; "the team is a unit"

width ; breadth
the extent of something from side to side


Z
zeroth law of thermodynamics
the law that if two bodies are in thermal equilibrium with a third body then the first two bodies are in thermal equilibrium with each other


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