Glossary of Physics Terms

Glossary of Physics Terms

This glossary of physics is a list of definitions of terms and concepts relevant to physics, its sub-disciplines, and related fields, including mechanics, materials science, nuclear physics, particle physics, and thermodynamics.

Acceleration:

Rate of change of velocity with time

Artificial Satellite:

Man made objects moving in fixed circular orbits around the earth.

Atomic Physics:

The branch of Physics that deals with the study of the structure and properties of atoms.

Axis of rotation:

A straight line passing through the points of a rotating rigid body while the other points of the body move in circle about the axis.

Base quantity:

A quantity which can be expressed independently without the reference of any other quantity.

Base unit:

The units that describe base quantities.

Buoyant force:

The force acting on an object due to buoyancy of a liquid.

Center of gravity:

The point of a body where its weight acts.

Center of mass:

A point where an applied force causes the system to move without rotation.

Centrifugal force:

Centripetal reaction

Centripetal acceleration:

Acceleration produced by the centripetal force.

Circular motion:

Motion of a body along a circular path.

Coefficient of linear expansion:

Change in unit length caused by unit kelvin change in temperature.

Coefficient of volume expansion:

Change in unit volume caused by unit kelvin change in temperature.

Conduction:

Transfer of heat due to interaction of electrons or molecules.

Convection:

Transfer of heat by actual movement of molecules from place to cold place.

Couple:

When two equal and unlike parallel forces act at different points of a body they constitute a couple.

Deceleration:

Negative acceleration

Density:

Mass per unit volume

Derived quantity:

Such quantity which is expressed with reference to base quantities.

Derived units:

The units used to measure derived quantities.

Displacement:

The shortest distance between two points.

Distance:

Length of a path between two points.

Dynamics:

Study of motion of bodies under the action of forces.

Efficiency:

Ratio of output and input.

Effort arm:

The intermediate distance between fulcrum and effort.

Effort moment:

Product of effort and effort arm.

Effort:

Force applied on the machine.

Elastic potential energy:

Energy of a compressed or stretched soring.

Elasticity modulus:

Ratio of stress and strain

Elasticity:

The property of the solids because of which they restore their original when external force ceases to act.

Electromagnetism:

The branch of physics that deals with the study of the charges at rest motion their effects and their relationship with magnetism.

Energy:

Ability of a body to do work

Equilibrium:

A state where acceleration of a body is zero.

Evaporation:

The changing of a liquid into vapours from the surface of a the liquid without heating it.

Field force:

The gravitational pull of the Earth acting on the body whether the body is in contact with the Earth or not.

Force of gravitation:

The force due to which everybody of the universe attracts every other body.

Force:

The agent that changes or tends to change the state of a body.

Friction:

The force of resistance against the relative motion between two surfaces.

Fulcrum:

The point around which lever revolves.

Geophysics:

The branch of Physics that deals with the study of the internal structure of the Earth and tectonic plate motions etc.

Gravitational Acceleration:

Acceleration due to gravity of the Earth.

Gravitational field strength:

The gravitational force per unit mass

Gravitational field:

The field in a region in space in which a particle would experience a gravitational force.

Gravitational force:

Mutual force of attraction between the objects.

Gravitational potential energy:

Energy of a body due to its position in the gravitational field.

Heat capacity:

The quantity of thermal energy absorbed by a body for increase in its temperature.

Heat:

The branch of physics that deals with the nature of heat, modes of transfer of heat and effects of heat.

Heat:

The form of energy which transferred from one place to another because of temperature difference.

Horizontal component:

The component of a force which is along horizontal or x-direction.

Inertia:

The characteristics of a body due to which it resists against any changes in its state of rest or motion.

Input:

A work which is done on the machine.

Internal Energy:

The sum of K.E and P.E associated with the atoms, molecules and particles of a body.

Isolated system:

A group of a interacting bodies on which no force is acting.

Joule:

The amount of work done when a force of one newton displaces a body through one meter in the reaction of force.

Kilowatt-hour:

Work done more hour at a rate of one kilowatt

Kinematics:

Study of motion of bodies without taking into consideration the mass and forces.

Kinematic energy:

Energy of a body due to its motion.

Kinetic friction:

Friction during motion

Latent heat of fusion:

The quantity of heat required to change one kilogramme of a solid substance to liquid state during which its temperature remains constant.

Latent heat of vapourization:

The quantity of heat required to change the state of one kilogramme of a liquid to vapour or gaseous state during which its temperature remains constant.

Lever:

A strong bar revolving around some point.

Light year:

The unit of distance for celestial bodies equal to 9.46 x 1016 m.

Light:

The branch of physics that deals with the physical aspects of light and its properties, working and uses of optical instruments.

Like parallel forces:

Forces acting along parallel lines in the same direction.

Limiting friction:

The maximum value of static friction.

Line of action of a force:

The line along which a force acts.

Linear motion:

The motion of a body along a straight line.

Load arm:

The intermediate distance between fulcrum and load.

Load moment:

Product of load and load arm.

Load:

Resistance of lifted up weight.

Mass:

The characteristic of a body, which determines the acceleration produced by the application of a force.

Mechanical advantage:

Ratio of load and effort.

Mechanics:

The branch of Physics that deals with the motion of objects, causes and effects of motion.

Moment arm:

The perpendicular distance between the axis of rotation and the line of action of the force.

Momentum:

The product of mass and velocity of a body.

Motion:

If a body changes its position with respect to its surroundings.

Negative vector:

A vector which has the same magnitude but opposite direction of another vector.

Neutral equilibrium:

The condition of a body in which its centre of gravity neither rises nor becomes lower of its original position after being distributed.

Nuclear physics:

The branch of Physics that deals with the properties and behaviour of nuclei and the particles within the nuclei.

Orbital velocity:

The critical velocity of a satellite in order to keep on moving around the Earth at a specific height.

Output:

A work, which is done by the machine.

Parallel force:

The forces which are parallel to each other.

Perpendicular components:

The components of a force which are manually perpendicular to each other.

Physical quantities:

All measurable quantities.

Physics:

The branch of Science which explains the properties of matter and energy.

Plasma physics:

The branch of Physics that deals with the study of production, properties of the ionic state of matter – the fourth state of matter.

Position:

Location of a place or a point with respect to some reference point.

Potential Energy:

The energy possessed by a body due to its position.

Power:

Rate of doing work.

Prefixes:

The words or letters added before a unit and stand for the multiplies or submultiples of that unit.

Pressure:

The force acting normally per unit area.

Radiation:

Transfer of heat by intra red radiations requiring no medium for their transmission.

Random motion:

Motion without any consideration of time and direction.

Rate of flow of heat:

The amount of heat that flows in unit time.

Resolution of force:

Splitting up of a force into its components.

Rest:

If a body does not change its position with respect to its surroundings.

Resultant force:

Such a force, which shows the combined effect of two or more forces.

Restardation:

Negative acceleration.

Rolling friction:

The friction produced during the motion of one body over the other with the help of wheels.

Rotatory motion:

The motion in which a body moves around an axis passing through it.

Scalar:

A physical quantity which is completely described by its magnitude only.

Scientific method:

Logical applications of arguments that explain a certain phenomenon.

Significant figures:

In a measurement the correctly known digits and the first doubtful digit.

Simple machine:

A thing which helps in doing work more easily.

Sliding friction:

The friction between two surfaces sliding against each other.

Sound:

The branch of Physics that deals with the physical aspects of sound waves, their production, properties and applications.

Specific heat capacity:

The quantity of heat, which changes the temperature of one kilogramme mass by 1 K.

Speed:

Distance covered by a body in unit time.

Stability:

The property of a body which does not undergo any change without the application of an external agency.

Stable equilibrium:

The condition of a body in which it comes to its original position after being disturbed.

Static friction:

The force of friction arising due to an applied external force before motion.

Strain:

The change in the shape of an object under the action of an external force.

Stress:

Force acting on unit area of an object.

Surface tension:

The force acting along the surface of a liquid.

Temperature:

The degree of hotness or coldness of a body.

Tensile strain:

Change in length per unit original length.

Tension:

The force acting along a string.

Thermal conductivity:

The rate of flow of heat across the opposite faces of a meter cube maintained at a temperature difference of 1K.

Thermal equilibrium:

The property of a system when all parts of the system have the same temperature along with its surrounding.

Thermometer:

A device used to measure temperature.

Thermometry:

Art of measurement of temperature.

Torque:

The capacity of a force to rotate a body.

Translatory motion:

The motion of a body when it moves along a line without rotation.

Trigonometric ratios:

The ratios of the sides of right-angled triangle.

Uniform acceleration:

Equal changes in velocity in equal intervals of time.

Uniform speed:

Equal distances covered by a body in equal intervals of time.

Uniform velocity:

Equal changes in displacement in equal intervals of time.

Unlike parallel forces:

Forces that are parallel but have direction opposite to each other.

Unstable equilibrium:

The condition of a body in which it does not come to its original position after being disturbed.

Vector:

A physical quantity which is described completely by magnitude and direction.

Velocity:

Rate of change of displacement.

Vibratory motion:

Zig-zag motion of the molecules of gases and liquids.

Watt:

The power of a body if it does work at the rate of one joule per second.

Weight:

Force of gravitation acting on a body.

Work:

The product of force and displacement.

Young's modulus:

The ratio of stress to tensile strain.