JonyC/ScienceGlossary · Datasets at Hugging Face

term stringlengths 1 63 ⌀	category stringclasses 15 values	label int64 0 1	definition stringlengths 5 3.18k ⌀
capacitive reactance	Physics	1	An opposition to the change of voltage across an electrical circuit element. Capacitive reactance X C \scriptstyle {X_{C}}} is inversely proportional to the signal frequency f \scriptstyle {f}} (or angular frequency, ω) and the capacitance C \scriptstyle {C}} .
capacitor	Physics	1	A general term used when it is not necessary to state whether reference is made to an element, a unit or a capacitor bank.
carnot cycle	Physics	1	A theoretical ideal thermodynamic cycle proposed by French physicist Nicolas Léonard Sadi Carnot in 1824 and expanded upon by others in the 1830s and 1840s. It provides an upper limit on the efficiency that any classical thermodynamic engine can achieve during the conversion of heat into work, or conversely, the efficiency of a refrigeration system in creating a temperature difference by the application of work to the system. It is not an actual thermodynamic cycle but is a theoretical construct.
cartesian coordinate system	Physics	1	A coordinate system that specifies each point uniquely in a plane by a set of numerical coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, measured in the same unit of length. Each reference line is called a coordinate axis or just axis (plural axes) of the system, and the point where they meet is called the origin, at ordered pair (0, 0). The coordinates can also be defined as the positions of the perpendicular projections of the point onto the two axes, expressed as signed distances from the origin.
cathode	Physics	1	The electrode through which a conventional electric current flows out of a polarized electrical device; the direction of current flow is, by convention, opposite to the direction of electron flow, and so electrons flow into the cathode. In a galvanic cell, the cathode is the positive terminal or pole which accepts electrons flowing from the external part of an electrical circuit. However, in an electrolytic cell, the cathode is the wire or plate having excess negative charge, so named because positively charged cations tend to move towards it. Contrast anode.
cation	Physics	1	A positively charged ion. Contrast anion.
celsius scale	Physics	1	A scale and unit of measurement of temperature.
center of gravity	Physics	1	The point in a body around which the resultant torque due to gravity forces vanish. Near the surface of the earth, where gravity acts downward as a parallel force field, the center of gravity and the center of mass are the same.
center of mass	Physics	1	Within a given distribution of mass, the unique point in space at which the weighted relative position of the distributed mass sums to zero.
centigrade	Physics	1	See Celsius scale.
central-force problem	Physics	1	A classic problem in potential theory involving the determination of the motion of a particle in a single central potential field. The solutions to such problems are important in classical mechanics, since many naturally occurring forces, such as gravity and electromagnetism, are central forces.
centrifugal force	Physics	1	The apparent outward force that draws a rotating body away from the centre of rotation. It is caused by the inertia of the body as the body's path is continually redirected.
centripetal force	Physics	1	A force which keeps a body moving with a uniform speed along a circular path and is directed along the radius towards the centre.
cgh physics	Physics	1	Any attempt in mainstream physics to unify existing theories of relativity, gravitation, and quantum mechanics, particularly by envisioning the three universal constants fundamental to each field – the speed of light ( c c} ), the gravitational constant ( G G} ), and the Planck constant ( h h} ) – as the edges of a three-dimensional cube, at each corner of which is positioned a major sub-field within theoretical physics according to which of the three constants are accounted for by that sub-field and which are ignored. One corner of this so-called "cube of theoretical physics", where all three constants are accounted for simultaneously, has not yet been satisfactorily described: quantum gravity.
chain reaction	Physics	1	A sequence of reactions in which a reactive product or byproduct causes additional similar reactions to take place.
chemical physics	Physics	1	A branch of chemistry and physics that studies chemical processes from the point of view of physics by investigating physicochemical phenomena using techniques from atomic and molecular physics and condensed matter physics.
classical mechanics	Physics	1	A sub-field of mechanics concerned with the set of physical laws describing the motion of bodies under the collective actions of a system of forces.
cohesion	Physics	1	The tendency of similar particles or surfaces to cling to one another. Contrast adhesion.
compton scattering	Physics	1	A type of light–matter interaction in which a photon is scattered by a charged particle, usually an electron, which results in part of the energy of the photon being transferred to the recoiling electron; a resulting decrease in the energy of the photon is called the Compton effect. The opposite phenomenon occurs in inverse Compton scattering, when a charged particle transfers part of its energy to a photon.
condensed matter physics	Physics	1	A branch of physics that studies the physical properties of condensed phases of matter.
convection	Physics	1	A method of moving heat energy. Found only in gases and liquids. Convection currents move heat from one location to another.
coulomb	Physics	1	Unit of electric charge derived from the ampere. It is defined as the charge transported by a steady current of 1 ampere in 1 second.
c	Physics	1	The SI derived unit of electric charge, defined as the charge transported by a constant current of one ampere in one second.
crest	Physics	1	The point on a wave with the maximum value or upward displacement within a cycle.
critical mass	Physics	1	The smallest amount of fissile material needed for a sustained nuclear chain reaction.
cube of theoretical physics	Physics	1	See cGh physics.
curvilinear motion	Physics	1	The motion of a moving particle or object that conforms to a known or fixed curve. Such motion is studied with two coordinate systems: planar motion and cylindrical motion.
cyclotron	Physics	1	A type of particle accelerator in which charged particles accelerate outwards from the center along a spiral path.
damping ratio	Physics	1	Any influence upon or within an oscillatory system that has the effect of reducing, restricting, or preventing its oscillations. Damping is a result of processes that dissipate the energy stored in the oscillation.
dc motor	Physics	1	A mechanically commutated electric motor powered by direct current.
deflection	Physics	1	The degree to which a structural element is displaced under a load. It may refer to an angle or a distance.
deformation	Physics	1	1. (mechanics)
density	Physics	1	How tightly a certain amount of matter (atoms or molecules) of a substance is compacted in a given volume. Density is commonly measured in grams per millilitre (g/ml) or cubic centimetre (g/cm3).
derivative	Physics	1	For a mathematical function of a real variable, a measurement of the sensitivity to change of the function value (output) with respect to a change in its argument (input); e.g. the derivative of the position of a moving object with respect to time is the object's velocity and measures how quickly the position of the object changes as time changes. Derivatives are a fundamental tool of calculus.
dielectric	Physics	1	An electrical insulator that can be polarized by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the material as they would in a conductor but only shift slightly from their equilibrium positions, with positive charges displaced in the direction of the field's flow and negative charges displaced in the opposite direction; this creates an internal electric field that reduces the larger field within the dielectric material.
displacement	Physics	1	1. (fluid) Occurs when an object is immersed in a fluid, pushing it out of the way and taking its place. The volume of the immersed object will be exactly equal to the volume of the displaced fluid, so that the volume of the immersed object can be deduced if the volume of the displaced fluid is measured.
distance	Physics	1	A numerical description of how far apart objects are.
doppler effect	Physics	1	An apparent shift in the frequency of sound or light. This is due to relative motion between the source of the sound or light and the observer.
drag	Physics	1	Sometimes called air resistance or fluid resistance, drag refers to forces that oppose the relative motion of an object through a fluid (a liquid or gas).
ductility	Physics	1	A solid material's ability to deform under tensile stress; this is often characterized by the material's ability to be stretched into a wire.
dynamics	Physics	1	The branch of classical mechanics that studies forces and torques and their effects on motion, as opposed to kinematics, which studies motion without reference to these forces.
elasticity	Physics	1	The ability of a solid to return to its original shape or form after it has been stretched or compressed.
electric charge	Physics	1	An excess of electrons on an object gives it a negative charge whereas a deficiency of electrons gives it a positive charge. Protons carry a positive charge and electrons carry a negative charge. Ions carry a positive or negative charge.
electric circuit	Physics	1	An electrical network consisting of a closed loop, giving a return path for the current.
electric current	Physics	1	A flow of electric charge through a conductive medium.
electric field	Physics	1	Any region where a charged object experiences an electric force.
electric power	Physics	1	The rate at which electric energy is transferred by an electric circuit.
electrical conductor	Physics	1	Any material which contains movable electric charges and therefore can conduct an electric current under the influence of an electric field.
electrical insulator	Physics	1	Any material whose internal electric charges do not flow freely and which therefore does not conduct an electric current under the influence of an electric field.
electrical network	Physics	1	An interconnection of electrical elements such as resistors, inductors, capacitors, voltage sources, current sources, and switches.
electrical resistance	Physics	1	For a given object, it is a measure of the opposition to the passage of electric current.
electricity	Physics	1	The set of physical phenomena associated with the presence and flow of electric charges.
electromagnet	Physics	1	A magnet consisting of a coil of insulated wire wrapped around a steel or iron core that is magnetised when a current flows through the wire.
electromagnetic field	Physics	1	A physical field produced by moving electrically charged objects.
electromagnetic radiation	Physics	1	A form of energy emitted and absorbed by charged particles, which exhibits wave-like behavior as it travels through space.
electromotive force	Physics	1	The electrical intensity or "pressure" developed by a source of electrical energy such as a battery or generator and measured in volts. Any device that converts other forms of energy into electrical energy provides electromotive force as its output.
electron	Physics	1	A light subatomic particle with negative charge, found in the space surrounding an atomic nucleus.
electron paramagnetic resonance	Physics	1	A method for studying materials with unpaired electrons which makes use of the Zeeman effect. It shares some basic principles with nuclear magnetic resonance (NMR).
electronvolt	Physics	1	A unit of energy equal to approximately 1.6×10−19 joule. By definition, it is the amount of energy gained by the charge of a single electron moved across an electric potential difference of one volt.
ev	Physics	1	A unit of energy equal to approximately 1.6×10−19 joule. By definition, it is the amount of energy gained by the charge of a single electron moved across an electric potential difference of one volt.
electronegativity	Physics	1	A chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself.
electronics	Physics	1	A field that deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes, and integrated circuits as well as associated passive interconnection technologies.
energy	Physics	1	The ability to do work.
endothermic	Physics	1	An adjective used to refer to a process or reaction in which a system absorbs energy from its surroundings, usually in the form of heat but also in the form of light, electricity, or sound. Contrast exothermic.
entropy	Physics	1	A quantity which describes the randomness of a substance or system.
escape velocity	Physics	1	The velocity at which the kinetic energy plus the gravitational potential energy of an object is zero. It is the speed needed to "escape" from a gravitational field without further propulsion.
exothermic	Physics	1	An adjective used to refer to a process or reaction that releases energy from a system, usually in the form of heat but also in the form of light, electricity, or sound. Contrast endothermic.
falling bodies	Physics	1	Objects that are moving towards a body with greater gravitational influence, such as a planet.
fermion	Physics	1	A type of particle that behaves according to Fermi–Dirac statistics, obeys the Pauli exclusion principle, and possesses half-integer spin. Fermions include all quarks and leptons, as well as all composite particles made of an odd number of these (such as all baryons and many atoms and nuclei). Fermions constitute one of two main classes of particles, the other being bosons.
fission	Physics	1	Either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei), often producing free neutrons and photons (in the form of gamma rays) and releasing relatively large amounts of energy.
force	Physics	1	A push or a pull that causes an object to change its shape, direction and/or motion.
f	Physics	1	A push or pull. Any interaction that, when unopposed, will change the motion of a physical body. A force has both magnitude and direction, making it a vector quantity. The SI unit used to measure force is the newton.
free fall	Physics	1	Any motion of a body where its own weight is the only force acting upon it.
freezing point	Physics	1	The temperature at which a substance changes state from liquid to solid.
fusion	Physics	1	A nuclear reaction in which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus.
gamma ray	Physics	1	High-energy electromagnetic radiation.
gravitation	Physics	1	A natural phenomenon by which physical bodies attract each other with a force proportional to their masses.
gravitational constant	Physics	1	A physical constant involved in the calculation of gravitational force between two bodies.
g	Physics	1	A physical constant involved in the calculation of gravitational force between two bodies.
gravitational energy	Physics	1	The potential energy associated with the gravitational field.
gravitational field	Physics	1	A model used to explain the influence that a massive body extends into the space around itself, producing a force (gravity) on another massive body. Thus, a gravitational field is used to explain and represent gravitational phenomena. It is measured in newtons per kilogram (N/kg).
gravitational potential	Physics	1	The gravitational potential at a location is equal to the work (energy transferred) per unit mass that is done by the force of gravity to move an object to a fixed reference location.
gravitational wave	Physics	1	A ripple in the curvature of spacetime that propagates as a wave and is generated in certain gravitational interactions, travelling outward from their source.
gravity	Physics	1	See gravitation.
hadron	Physics	1	‘Heavy’ subatomic particles each made up of three quarks. Protons and neutrons are the most well known hadrons.
half-life	Physics	1	Used in nuclear physics to describe the time required for half of a given sample to undergo radioactive decay. Used more generally to characterise any type of exponential decay.
heat	Physics	1	Heat energy: the transfer of energy in materials from the random movement of the particles in that material. The greater the random movement of particles the more heat energy the material has. Temperature is a measure of the heat energy of a material.Heat: the flow of energy from a warm object to a cooler object.
hertz	Physics	1	The SI unit of frequency, defined as the number of cycles per second of a periodic phenomenon.
homeokinetics	Physics	1	The physics of complex, self-organizing systems.
ice point	Physics	1	A physical process that results in the phase transition of a substance from a liquid to a solid.
impedance	Physics	1	The measure of the opposition that a circuit presents to a current when a voltage is applied.
implosion	Physics	1	The change in momentum, which is equal to the average net external force multiplied by the time this force acts.
impulse	Physics	1	The change in momentum, which is equal to the average net external force multiplied by the time this force acts.
inertia	Physics	1	The resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion.
international system of units	Physics	1	The modern form of the metric system, comprising a system of units of measurement devised around seven base units and the convenience of the number ten.
si	Physics	1	The modern form of the metric system, comprising a system of units of measurement devised around seven base units and the convenience of the number ten.
ion	Physics	1	An atom or group of atoms that has gained or lost electrons and has an electrical charge.
ionic bond	Physics	1	A type of chemical bond formed through an electrostatic attraction between two oppositely charged ions.
ionization	Physics	1	The process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or other ions.
isotope	Physics	1	Different forms of atoms of the same element. Within the nucleus, there is the same number of protons but a different number of neutrons, giving each isotope a different atomic mass.

capacitive reactance

Physics

1

An opposition to the change of voltage across an electrical circuit element. Capacitive reactance X C \scriptstyle {X_{C}}} is inversely proportional to the signal frequency f \scriptstyle {f}} (or angular frequency, ω) and the capacitance C \scriptstyle {C}} .

capacitor

Physics

1

A general term used when it is not necessary to state whether reference is made to an element, a unit or a capacitor bank.

carnot cycle

Physics

1

A theoretical ideal thermodynamic cycle proposed by French physicist Nicolas Léonard Sadi Carnot in 1824 and expanded upon by others in the 1830s and 1840s. It provides an upper limit on the efficiency that any classical thermodynamic engine can achieve during the conversion of heat into work, or conversely, the efficiency of a refrigeration system in creating a temperature difference by the application of work to the system. It is not an actual thermodynamic cycle but is a theoretical construct.

cartesian coordinate system

Physics

1

A coordinate system that specifies each point uniquely in a plane by a set of numerical coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, measured in the same unit of length. Each reference line is called a coordinate axis or just axis (plural axes) of the system, and the point where they meet is called the origin, at ordered pair (0, 0). The coordinates can also be defined as the positions of the perpendicular projections of the point onto the two axes, expressed as signed distances from the origin.

cathode

Physics

1

The electrode through which a conventional electric current flows out of a polarized electrical device; the direction of current flow is, by convention, opposite to the direction of electron flow, and so electrons flow into the cathode. In a galvanic cell, the cathode is the positive terminal or pole which accepts electrons flowing from the external part of an electrical circuit. However, in an electrolytic cell, the cathode is the wire or plate having excess negative charge, so named because positively charged cations tend to move towards it. Contrast anode.

cation

Physics

1

A positively charged ion. Contrast anion.

celsius scale

Physics

1

A scale and unit of measurement of temperature.

center of gravity

Physics

1

The point in a body around which the resultant torque due to gravity forces vanish. Near the surface of the earth, where gravity acts downward as a parallel force field, the center of gravity and the center of mass are the same.

center of mass

Physics

1

Within a given distribution of mass, the unique point in space at which the weighted relative position of the distributed mass sums to zero.

centigrade

Physics

1

See Celsius scale.

central-force problem

Physics

1

A classic problem in potential theory involving the determination of the motion of a particle in a single central potential field. The solutions to such problems are important in classical mechanics, since many naturally occurring forces, such as gravity and electromagnetism, are central forces.

centrifugal force

Physics

1

The apparent outward force that draws a rotating body away from the centre of rotation. It is caused by the inertia of the body as the body's path is continually redirected.

centripetal force

Physics

1

A force which keeps a body moving with a uniform speed along a circular path and is directed along the radius towards the centre.

cgh physics

Physics

1

Any attempt in mainstream physics to unify existing theories of relativity, gravitation, and quantum mechanics, particularly by envisioning the three universal constants fundamental to each field – the speed of light ( c c} ), the gravitational constant ( G G} ), and the Planck constant ( h h} ) – as the edges of a three-dimensional cube, at each corner of which is positioned a major sub-field within theoretical physics according to which of the three constants are accounted for by that sub-field and which are ignored. One corner of this so-called "cube of theoretical physics", where all three constants are accounted for simultaneously, has not yet been satisfactorily described: quantum gravity.

chain reaction

Physics

1

A sequence of reactions in which a reactive product or byproduct causes additional similar reactions to take place.

chemical physics

Physics

1

A branch of chemistry and physics that studies chemical processes from the point of view of physics by investigating physicochemical phenomena using techniques from atomic and molecular physics and condensed matter physics.

classical mechanics

Physics

1

A sub-field of mechanics concerned with the set of physical laws describing the motion of bodies under the collective actions of a system of forces.

cohesion

Physics

1

The tendency of similar particles or surfaces to cling to one another. Contrast adhesion.

compton scattering

Physics

1

A type of light–matter interaction in which a photon is scattered by a charged particle, usually an electron, which results in part of the energy of the photon being transferred to the recoiling electron; a resulting decrease in the energy of the photon is called the Compton effect. The opposite phenomenon occurs in inverse Compton scattering, when a charged particle transfers part of its energy to a photon.

condensed matter physics

Physics

1

A branch of physics that studies the physical properties of condensed phases of matter.

convection

Physics

1

A method of moving heat energy. Found only in gases and liquids. Convection currents move heat from one location to another.

coulomb

Physics

1

Unit of electric charge derived from the ampere. It is defined as the charge transported by a steady current of 1 ampere in 1 second.

c

Physics

1

The SI derived unit of electric charge, defined as the charge transported by a constant current of one ampere in one second.

crest

Physics

1

The point on a wave with the maximum value or upward displacement within a cycle.

critical mass

Physics

1

The smallest amount of fissile material needed for a sustained nuclear chain reaction.

cube of theoretical physics

Physics

1

See cGh physics.

curvilinear motion

Physics

1

The motion of a moving particle or object that conforms to a known or fixed curve. Such motion is studied with two coordinate systems: planar motion and cylindrical motion.

cyclotron

Physics

1

A type of particle accelerator in which charged particles accelerate outwards from the center along a spiral path.

damping ratio

Physics

1

Any influence upon or within an oscillatory system that has the effect of reducing, restricting, or preventing its oscillations. Damping is a result of processes that dissipate the energy stored in the oscillation.

dc motor

Physics

1

A mechanically commutated electric motor powered by direct current.

deflection

Physics

1

The degree to which a structural element is displaced under a load. It may refer to an angle or a distance.

deformation

Physics

1

1. (mechanics)

density

Physics

1

How tightly a certain amount of matter (atoms or molecules) of a substance is compacted in a given volume. Density is commonly measured in grams per millilitre (g/ml) or cubic centimetre (g/cm3).

derivative

Physics

1

For a mathematical function of a real variable, a measurement of the sensitivity to change of the function value (output) with respect to a change in its argument (input); e.g. the derivative of the position of a moving object with respect to time is the object's velocity and measures how quickly the position of the object changes as time changes. Derivatives are a fundamental tool of calculus.

dielectric

Physics

1

An electrical insulator that can be polarized by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the material as they would in a conductor but only shift slightly from their equilibrium positions, with positive charges displaced in the direction of the field's flow and negative charges displaced in the opposite direction; this creates an internal electric field that reduces the larger field within the dielectric material.

displacement

Physics

1

1. (fluid) Occurs when an object is immersed in a fluid, pushing it out of the way and taking its place. The volume of the immersed object will be exactly equal to the volume of the displaced fluid, so that the volume of the immersed object can be deduced if the volume of the displaced fluid is measured.

distance

Physics

1

A numerical description of how far apart objects are.

doppler effect

Physics

1

An apparent shift in the frequency of sound or light. This is due to relative motion between the source of the sound or light and the observer.

drag

Physics

1

Sometimes called air resistance or fluid resistance, drag refers to forces that oppose the relative motion of an object through a fluid (a liquid or gas).

ductility

Physics

1

A solid material's ability to deform under tensile stress; this is often characterized by the material's ability to be stretched into a wire.

dynamics

Physics

1

The branch of classical mechanics that studies forces and torques and their effects on motion, as opposed to kinematics, which studies motion without reference to these forces.

elasticity

Physics

1

The ability of a solid to return to its original shape or form after it has been stretched or compressed.

electric charge

Physics

1

An excess of electrons on an object gives it a negative charge whereas a deficiency of electrons gives it a positive charge. Protons carry a positive charge and electrons carry a negative charge. Ions carry a positive or negative charge.

electric circuit

Physics

1

An electrical network consisting of a closed loop, giving a return path for the current.

electric current

Physics

1

A flow of electric charge through a conductive medium.

electric field

Physics

1

Any region where a charged object experiences an electric force.

electric power

Physics

1

The rate at which electric energy is transferred by an electric circuit.

electrical conductor

Physics

1

Any material which contains movable electric charges and therefore can conduct an electric current under the influence of an electric field.

electrical insulator

Physics

1

Any material whose internal electric charges do not flow freely and which therefore does not conduct an electric current under the influence of an electric field.

electrical network

Physics

1

An interconnection of electrical elements such as resistors, inductors, capacitors, voltage sources, current sources, and switches.

electrical resistance

Physics

1

For a given object, it is a measure of the opposition to the passage of electric current.

electricity

Physics

1

The set of physical phenomena associated with the presence and flow of electric charges.

electromagnet

Physics

1

A magnet consisting of a coil of insulated wire wrapped around a steel or iron core that is magnetised when a current flows through the wire.

electromagnetic field

Physics

1

A physical field produced by moving electrically charged objects.

electromagnetic radiation

Physics

1

A form of energy emitted and absorbed by charged particles, which exhibits wave-like behavior as it travels through space.

electromotive force

Physics

1

The electrical intensity or "pressure" developed by a source of electrical energy such as a battery or generator and measured in volts. Any device that converts other forms of energy into electrical energy provides electromotive force as its output.

electron

Physics

1

A light subatomic particle with negative charge, found in the space surrounding an atomic nucleus.

electron paramagnetic resonance

Physics

1

A method for studying materials with unpaired electrons which makes use of the Zeeman effect. It shares some basic principles with nuclear magnetic resonance (NMR).

electronvolt

Physics

1

A unit of energy equal to approximately 1.6×10−19 joule. By definition, it is the amount of energy gained by the charge of a single electron moved across an electric potential difference of one volt.

ev

Physics

1

A unit of energy equal to approximately 1.6×10−19 joule. By definition, it is the amount of energy gained by the charge of a single electron moved across an electric potential difference of one volt.

electronegativity

Physics

1

A chemical property that describes the tendency of an atom or a functional group to attract electrons (or electron density) towards itself.

electronics

Physics

1

A field that deals with electrical circuits that involve active electrical components such as vacuum tubes, transistors, diodes, and integrated circuits as well as associated passive interconnection technologies.

energy

Physics

1

The ability to do work.

endothermic

Physics

1

An adjective used to refer to a process or reaction in which a system absorbs energy from its surroundings, usually in the form of heat but also in the form of light, electricity, or sound. Contrast exothermic.

entropy

Physics

1

A quantity which describes the randomness of a substance or system.

escape velocity

Physics

1

The velocity at which the kinetic energy plus the gravitational potential energy of an object is zero. It is the speed needed to "escape" from a gravitational field without further propulsion.

exothermic

Physics

1

An adjective used to refer to a process or reaction that releases energy from a system, usually in the form of heat but also in the form of light, electricity, or sound. Contrast endothermic.

falling bodies

Physics

1

Objects that are moving towards a body with greater gravitational influence, such as a planet.

fermion

Physics

1

A type of particle that behaves according to Fermi–Dirac statistics, obeys the Pauli exclusion principle, and possesses half-integer spin. Fermions include all quarks and leptons, as well as all composite particles made of an odd number of these (such as all baryons and many atoms and nuclei). Fermions constitute one of two main classes of particles, the other being bosons.

fission

Physics

1

Either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei), often producing free neutrons and photons (in the form of gamma rays) and releasing relatively large amounts of energy.

force

Physics

1

A push or a pull that causes an object to change its shape, direction and/or motion.

f

Physics

1

A push or pull. Any interaction that, when unopposed, will change the motion of a physical body. A force has both magnitude and direction, making it a vector quantity. The SI unit used to measure force is the newton.

free fall

Physics

1

Any motion of a body where its own weight is the only force acting upon it.

freezing point

Physics

1

The temperature at which a substance changes state from liquid to solid.

fusion

Physics

1

A nuclear reaction in which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus.

gamma ray

Physics

1

High-energy electromagnetic radiation.

gravitation

Physics

1

A natural phenomenon by which physical bodies attract each other with a force proportional to their masses.

gravitational constant

Physics

1

A physical constant involved in the calculation of gravitational force between two bodies.

g

Physics

1

A physical constant involved in the calculation of gravitational force between two bodies.

gravitational energy

Physics

1

The potential energy associated with the gravitational field.

gravitational field

Physics

1

A model used to explain the influence that a massive body extends into the space around itself, producing a force (gravity) on another massive body. Thus, a gravitational field is used to explain and represent gravitational phenomena. It is measured in newtons per kilogram (N/kg).

gravitational potential

Physics

1

The gravitational potential at a location is equal to the work (energy transferred) per unit mass that is done by the force of gravity to move an object to a fixed reference location.

gravitational wave

Physics

1

A ripple in the curvature of spacetime that propagates as a wave and is generated in certain gravitational interactions, travelling outward from their source.

gravity

Physics

1

See gravitation.

hadron

Physics

1

‘Heavy’ subatomic particles each made up of three quarks. Protons and neutrons are the most well known hadrons.

half-life

Physics

1

Used in nuclear physics to describe the time required for half of a given sample to undergo radioactive decay. Used more generally to characterise any type of exponential decay.

heat

Physics

1

Heat energy: the transfer of energy in materials from the random movement of the particles in that material. The greater the random movement of particles the more heat energy the material has. Temperature is a measure of the heat energy of a material.Heat: the flow of energy from a warm object to a cooler object.

hertz

Physics

1

The SI unit of frequency, defined as the number of cycles per second of a periodic phenomenon.

homeokinetics

Physics

1

The physics of complex, self-organizing systems.

ice point

Physics

1

A physical process that results in the phase transition of a substance from a liquid to a solid.

impedance

Physics

1

The measure of the opposition that a circuit presents to a current when a voltage is applied.

implosion

Physics

1

The change in momentum, which is equal to the average net external force multiplied by the time this force acts.

impulse

Physics

1

The change in momentum, which is equal to the average net external force multiplied by the time this force acts.

inertia

Physics

1

The resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion.

international system of units

Physics

1

The modern form of the metric system, comprising a system of units of measurement devised around seven base units and the convenience of the number ten.

si

Physics

1

The modern form of the metric system, comprising a system of units of measurement devised around seven base units and the convenience of the number ten.

ion

Physics

1

An atom or group of atoms that has gained or lost electrons and has an electrical charge.

ionic bond

Physics

1

A type of chemical bond formed through an electrostatic attraction between two oppositely charged ions.

ionization

Physics

1

The process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or other ions.

isotope

Physics

1

Different forms of atoms of the same element. Within the nucleus, there is the same number of protons but a different number of neutrons, giving each isotope a different atomic mass.