Glossary

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Glossary Entries
Word(s)	Definition	Source
beat frequency	frequency of beats produced by sound waves that differ in frequency	OpenStax
beats	constructive and destructive interference of two or more frequencies of sound	OpenStax
bow wake	v-shaped disturbance created when the wave source moves faster than the wave propagation speed	OpenStax
Doppler effect	alteration in the observed frequency of a sound due to motion of either the source or the observer	OpenStax
Doppler shift	actual change in frequency due to relative motion of source and observer	OpenStax
fundamental	the lowest-frequency resonance	OpenStax
harmonics	the term used to refer collectively to the fundamental and its overtones	OpenStax
hearing	perception of sound	OpenStax
loudness	perception of sound intensity	OpenStax
notes	basic unit of music with specific names, combined to generate tunes	OpenStax
overtones	all resonant frequencies higher than the fundamental	OpenStax
phon	numerical unit of loudness	OpenStax
pitch	perception of the frequency of a sound	OpenStax
shock wave	wave front that is produced when a sound source moves faster than the speed of sound	OpenStax
sonic boom	loud noise that occurs as a shock wave as it sweeps along the ground	OpenStax
sound	traveling pressure wave that may be periodic; the wave can be modeled as a pressure wave or as an oscillation of molecules	OpenStax
sound intensity level	unitless quantity telling you the level of the sound relative to a fixed standard	OpenStax
sound pressure level	ratio of the pressure amplitude to a reference pressure	OpenStax
timbre	number and relative intensity of multiple sound frequencies	OpenStax
transducer	device that converts energy of a signal into measurable energy form, for example, a microphone converts sound waves into an electrical signal	OpenStax
antinode	location of maximum amplitude in standing waves	OpenStax
constructive interference	when two waves arrive at the same point exactly in phase; that is, the crests of the two waves are precisely aligned, as are the troughs	OpenStax
destructive interference	when two identical waves arrive at the same point exactly out of phase; that is, precisely aligned crest to trough	OpenStax
fixed boundary condition	when the medium at a boundary is fixed in place so it cannot move	OpenStax
free boundary condition	exists when the medium at the boundary is free to move	OpenStax
fundamental frequency	lowest frequency that will produce a standing wave	OpenStax
intensity (I)	power per unit area	OpenStax
interference	overlap of two or more waves at the same point and time	OpenStax
linear wave equation	equation describing waves that result from a linear restoring force of the medium; any function that is a solution to the wave equation describes a wave moving in the positive x-direction or the negative x-direction with a constant wave speed v	OpenStax
longitudinal wave	wave in which the disturbance is parallel to the direction of propagation	OpenStax
mechanical wave	wave that is governed by Newton’s laws and requires a medium	OpenStax
node	point where the string does not move; more generally, nodes are where the wave disturbance is zero in a standing wave	OpenStax
normal mode	possible standing wave pattern for a standing wave on a string	OpenStax
overtone	frequency that produces standing waves and is higher than the fundamental frequency	OpenStax
pulse	single disturbance that moves through a medium, transferring energy but not mass	OpenStax
standing wave	wave that can bounce back and forth through a particular region, effectively becoming stationary	OpenStax
superposition	phenomenon that occurs when two or more waves arrive at the same point	OpenStax
transverse wave	wave in which the disturbance is perpendicular to the direction of propagation	OpenStax
wave	disturbance that moves from its source and carries energy	OpenStax
wave function	mathematical model of the position of particles of the medium	OpenStax
wave number	$\frac{2 \pi}{\lambda}$	OpenStax
wave speed	magnitude of the wave velocity	OpenStax
wave velocity	velocity at which the disturbance moves; also called the propagation velocity	OpenStax
wavelength	distance between adjacent identical parts of a wave	OpenStax
amplitude (A)	maximum displacement from the equilibrium position of an object oscillating around the equilibrium position	OpenStax
critically damped	condition in which the damping of an oscillator causes it to return as quickly as possible to its equilibrium position without oscillating back and forth about this position	OpenStax
elastic potential energy	potential energy stored as a result of deformation of an elastic object, such as the stretching of a spring	OpenStax
equilibrium position	position where the spring is neither stretched nor compressed	OpenStax
force constant (k)	characteristic of a spring which is defined as the ratio of the force applied to the spring to the displacement caused by the force	OpenStax
frequency (f)	number of events per unit of time	OpenStax
natural angular frequency	angular frequency of a system oscillating in SHM	OpenStax
oscillation	single fluctuation of a quantity, or repeated and regular fluctuations of a quantity, between two extreme values around an equilibrium or average value	OpenStax
overdamped	condition in which damping of an oscillator causes it to return to equilibrium without oscillating; oscillator moves more slowly toward equilibrium than in the critically damped system	OpenStax
period (T)	time taken to complete one oscillation	OpenStax
periodic motion	motion that repeats itself at regular time intervals	OpenStax
phase shift	angle, in radians, that is used in a cosine or sine function to shift the function left or right, used to match up the function with the initial conditions of data	OpenStax
physical pendulum	any extended object that swings like a pendulum	OpenStax
resonance	large amplitude oscillations in a system produced by a small amplitude driving force, which has a frequency equal to the natural frequency	OpenStax
restoring force	force acting in opposition to the force caused by a deformation	OpenStax
simple harmonic motion (SHM)	oscillatory motion in a system where the restoring force is proportional to the displacement, which acts in the direction opposite to the displacement	OpenStax
simple harmonic oscillator	a device that oscillates in SHM where the restoring force is proportional to the displacement and acts in the direction opposite to the displacement	OpenStax
simple pendulum	point mass, called a pendulum bob, attached to a near massless string	OpenStax
stable equilibrium point	point where the net force on a system is zero, but a small displacement of the mass will cause a restoring force that points toward the equilibrium point	OpenStax
torsional pendulum	any suspended object that oscillates by twisting its suspension	OpenStax
underdamped	condition in which damping of an oscillator causes the amplitude of oscillations of a damped harmonic oscillator to decrease over time, eventually approaching zero	OpenStax
absolute pressure	sum of gauge pressure and atmospheric pressure	OpenStax
Achimedes' principle	buoyant force on an object equals the weight of the fluid it displaces	OpenStax
Bernoulli's equation	equation resulting from applying conservation of energy to an incompressible frictionless fluid: $$p + \frac{1}{2} \rho v^{2} +\rho gh = constant,$$throughout the fluid	OpenStax
Bernoulli's principle	Bernoulli's equation applied at constant depth:$$p_{1} + \frac{1}{2} \rho v_{1}^{2} = p_{2} + \frac{1}{2} \rho v_{2}^{2}$$	OpenStax
buoyant force	net upward force on any object in any fluid due to the pressure difference at different depths	OpenStax
density	mass per unit volume of a substance or object	OpenStax
flow rate	abbreviated Q, it is the volume V that flows past a particular point during a time t, or Q = $\frac{dV}{dt}$	OpenStax
fluids	liquids and gases; a fluid is a state of matter that yields to shearing forces	OpenStax
gauge pressure	pressure relative to atmospheric pressure	OpenStax
hydraulic jack	simple machine that uses cylinders of different diameters to distribute force	OpenStax
hydrostatic equilibrium	state at which water is not flowing, or is static	OpenStax
ideal fluid	fluid with negligible viscosity	OpenStax
laminar flow	type of fluid flow in which layers do not mix	OpenStax
Pascal's principle	change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container	OpenStax
Poiseuille's law	rate of laminar flow of an incompressible fluid in a tube: $$Q = \frac{(p_{2} - p_{1}) \pi r^{4}}{8 \eta l} \ldotp$$	OpenStax
Poiseuille’s law for resistance	resistance to laminar flow of an incompressible fluid in a tube: $$R = \frac{8 \eta l}{\pi r^{4}}$$	OpenStax
pressure	force per unit area exerted perpendicular to the area over which the force acts	OpenStax
Reynolds number	dimensionless parameter that can reveal whether a particular flow is laminar or turbulent	OpenStax
specific gravity	ratio of the density of an object to a fluid (usually water)	OpenStax
turbulence	fluid flow in which layers mix together via eddies and swirls	OpenStax
turbulent flow	type of fluid flow in which layers mix together via eddies and swirls	OpenStax
viscosity	measure of the internal friction in a fluid	OpenStax
action-at-a-distance force	type of force exerted without physical contact	OpenStax
aphelion	farthest point from the Sun of an orbiting body; the corresponding term for the Moon’s farthest point from Earth is the apogee	OpenStax
apparent weight	reading of the weight of an object on a scale that does not account for acceleration	OpenStax
black hole	mass that becomes so dense, that it collapses in on itself, creating a singularity at the center surround by an event horizon	OpenStax
escape velocity	initial velocity an object needs to escape the gravitational pull of another; it is more accurately defined as the velocity of an object with zero total mechanical energy	OpenStax
event horizon	location of the Schwarzschild radius and is the location near a black hole from within which no object, even light, can escape	OpenStax
gravitational field	vector field that surrounds the mass creating the field; the field is represented by field lines, in which the direction of the field is tangent to the lines, and the magnitude (or field strength) is inversely proportional to the spacing of the lines; other masses respond to this field	OpenStax
gravitationally bound	two object are gravitationally bound if their orbits are closed; gravitationally bound systems have a negative total mechanical energy	OpenStax
Kepler’s first law	law stating that every planet moves along an ellipse, with the Sun located at a focus of the ellipse	OpenStax
Kepler’s second law	law stating that a planet sweeps out equal areas in equal times, meaning it has a constant areal velocity	OpenStax
Kepler’s third law	law stating that the square of the period is proportional to the cube of the semi-major axis of the orbit	OpenStax
neap tide	low tide created when the Moon and the Sun form a right triangle with Earth	OpenStax
neutron star	most compact object known—outside of a black hole itself	OpenStax
Newton’s law of gravitation	every mass attracts every other mass with a force proportional to the product of their masses, inversely proportional to the square of the distance between them, and with direction along the line connecting the center of mass of each	OpenStax
non-Euclidean geometry	geometry of curved space, describing the relationships among angles and lines on the surface of a sphere, hyperboloid, etc.	OpenStax
orbital period	time required for a satellite to complete one orbit	OpenStax
orbital speed	speed of a satellite in a circular orbit; it can be also be used for the instantaneous speed for noncircular orbits in which the speed is not constant	OpenStax
perihelion	point of closest approach to the Sun of an orbiting body; the corresponding term for the Moon’s closest approach to Earth is the perigee	OpenStax
principle of equivalence	part of the general theory of relativity, it states that there no difference between free fall and being weightless, or a uniform gravitational field and uniform acceleration	OpenStax
Schwarzschild radius	critical radius (RS) such that if a mass were compressed to the extent that its radius becomes less than the Schwarzschild radius, then the mass will collapse to a singularity, and anything that passes inside that radius cannot escape	OpenStax
space-time	concept of space-time is that time is essentially another coordinate that is treated the same way as any individual spatial coordinate; in the equations that represent both special and general relativity, time appears in the same context as do the spatial coordinates	OpenStax
spring tide	high tide created when the Moon, the Sun, and Earth are along one line	OpenStax
theory of general relativity	Einstein’s theory for gravitation and accelerated reference frames; in this theory, gravitation is the result of mass and energy distorting the space-time around it; it is also often referred to as Einstein’s theory of gravity	OpenStax
tidal force	difference between the gravitational force at the center of a body and that at any other location on the body; the tidal force stretches the body	OpenStax
universal gravitational constant	constant representing the strength of the gravitational force, that is believed to be the same throughout the universe	OpenStax
breaking stress (ultimate stress)	value of stress at the fracture point	OpenStax
bulk modulus	elastic modulus for the bulk stress	OpenStax
bulk strain (or volume strain)	strain under the bulk stress, given as fractional change in volume	OpenStax
bulk stress (or volume stress)	stress caused by compressive forces, in all directions	OpenStax
center of gravity	point where the weight vector is attached	OpenStax
compressibility	reciprocal of the bulk modulus	OpenStax
compressive strain	strain that occurs when forces are contracting an object, causing its shortening	OpenStax
compressive stress	stress caused by compressive forces, only in one direction	OpenStax
elastic	object that comes back to its original size and shape when the load is no longer present	OpenStax
elastic limit	stress value beyond which material no longer behaves elastically and becomes permanently deformed	OpenStax
elastic modulus	proportionality constant in linear relation between stress and strain, in SI pascals	OpenStax
equilibrium	body is in equilibrium when its linear and angular accelerations are both zero relative to an inertial frame of reference	OpenStax
first equilibrium condition	expresses translational equilibrium; all external forces acting on the body balance out and their vector sum is zero	OpenStax
gravitational torque	torque on the body caused by its weight; it occurs when the center of gravity of the body is not located on the axis of rotation	OpenStax
linearity limit (proportionality limit)	largest stress value beyond which stress is no longer proportional to strain	OpenStax
normal pressure	pressure of one atmosphere, serves as a reference level for pressure	OpenStax
pascal (Pa)	SI unit of stress, SI unit of pressure	OpenStax
plastic behavior	material deforms irreversibly, does not go back to its original shape and size when load is removed and stress vanishes	OpenStax
pressure	force pressing in normal direction on a surface per the surface area, the bulk stress in fluids	OpenStax
second equilibrium condition	expresses rotational equilibrium; all torques due to external forces acting on the body balance out and their vector sum is zero	OpenStax
shear modulus	elastic modulus for shear stress	OpenStax
shear strain	strain caused by shear stress	OpenStax
shear stress	stress caused by shearing forces	OpenStax
static equilibrium	body is in static equilibrium when it is at rest in our selected inertial frame of reference	OpenStax
strain	dimensionless quantity that gives the amount of deformation of an object or medium under stress	OpenStax
stress	quantity that contains information about the magnitude of force causing deformation, defined as force per unit area	OpenStax
stress-strain diagram	graph showing the relationship between stress and strain, characteristic of a material	OpenStax
tensile strain	strain under tensile stress, given as fractional change in length, which occurs when forces are stretching an object, causing its elongation	OpenStax
tensile stress	stress caused by tensile forces, only in one direction, which occurs when forces are stretching an object, causing its elongation	OpenStax
Young’s modulus	elastic modulus for tensile or compressive stress	OpenStax
angular momentum	rotational analog of linear momentum, found by taking the product of moment of inertia and angular velocity	OpenStax
law of conservation of angular momentum	angular momentum is conserved, that is, the initial angular momentum is equal to the final angular momentum when no external torque is applied to the system	OpenStax
precession	circular motion of the pole of the axis of a spinning object around another axis due to a torque	OpenStax
rolling motion	combination of rotational and translational motion with or without slipping	OpenStax
angular acceleration	time rate of change of angular velocity	OpenStax
angular position	angle a body has rotated through in a fixed coordinate system	OpenStax
angular velocity	time rate of change of angular position	OpenStax
instantaneous angular acceleration	derivative of angular velocity with respect to time	OpenStax
instantaneous angular velocity	derivative of angular position with respect to time	OpenStax
kinematics of rotational motion	describes the relationships among rotation angle, angular velocity, angular acceleration, and time	OpenStax
lever arm	perpendicular distance from the line that the force vector lies on to a given axis	OpenStax
linear mass density	the mass per unit length λ of a one dimensional object	OpenStax
moment of inertia	rotational mass of rigid bodies that relates to how easy or hard it will be to change the angular velocity of the rotating rigid body	OpenStax
Newton’s second law for rotation	sum of the torques on a rotating system equals its moment of inertia times its angular acceleration	OpenStax
parallel axis	axis of rotation that is parallel to an axis about which the moment of inertia of an object is known	OpenStax
parallel-axis theorem	if the moment of inertia is known for a given axis, it can be found for any axis parallel to it	OpenStax
rotational dynamics	analysis of rotational motion using the net torque and moment of inertia to find the angular acceleration	OpenStax
rotational kinetic energy	kinetic energy due to the rotation of an object; this is part of its total kinetic energy	OpenStax
rotational work	work done on a rigid body due to the sum of the torques integrated over the angle through with the body rotates	OpenStax
surface mass density	mass per unit area $\sigma$ of a two dimensional object	OpenStax
torque	cross product of a force and a lever arm to a given axis	OpenStax
total linear acceleration	vector sum of the centripetal acceleration vector and the tangential acceleration vector	OpenStax
work-energy theorem for rotation	the total rotational work done on a rigid body is equal to the change in rotational kinetic energy of the body	OpenStax
center of mass	weighted average position of the mass	OpenStax
closed system	system for which the mass is constant and the net external force on the system is zero	OpenStax
elastic	collision that conserves kinetic energy	OpenStax
explosion	single object breaks up into multiple objects; kinetic energy is not conserved in explosions	OpenStax
external force	force applied to an extended object that changes the momentum of the extended object as a whole	OpenStax
impulse	effect of applying a force on a system for a time interval; this time interval is usually small, but does not have to be	OpenStax
impulse-momentum theorem	change of momentum of a system is equal to the impulse applied to the system	OpenStax
inelastic	collision that does not conserve kinetic energy	OpenStax
internal force	force that the simple particles that make up an extended object exert on each other. Internal forces can be attractive or repulsive	OpenStax
Law of Conservation of Momentum	total momentum of a closed system cannot change	OpenStax
linear mass density	$\lambda$, expressed as the number of kilograms of material per meter	OpenStax
momentum	measure of the quantity of motion that an object has; it takes into account both how fast the object is moving, and its mass; specifically, it is the product of mass and velocity; it is a vector quantity	OpenStax
perfectly inelastic	collision after which all objects are motionless, the final kinetic energy is zero, and the loss of kinetic energy is a maximum	OpenStax
rocket equation	derived by the Soviet physicist Konstantin Tsiolkovsky in 1897, it gives us the change of velocity that the rocket obtains from burning a mass of fuel that decreases the total rocket mass from mi down to m	OpenStax
system	object or collection of objects whose motion is currently under investigation; however, your system is defined at the start of the problem, you must keep that definition for the entire problem	OpenStax
conservative force	force that does work independent of path	OpenStax
conserved quantity	one that cannot be created or destroyed, but may be transformed between different forms of itself	OpenStax
energy conservation	total energy of an isolated system is constant	OpenStax
equilibrium point	position where the assumed conservative, net force on a particle, given by the slope of its potential energy curve, is zero	OpenStax
exact differential	is the total differential of a function and requires the use of partial derivatives if the function involves more than one dimension	OpenStax
mechanical energy	sum of the kinetic and potential energies	OpenStax
non-conservative force	force that does work that depends on path	OpenStax
non-renewable	energy source that is not renewable, but is depleted by human consumption	OpenStax
potential energy	function of position, energy possessed by an object relative to the system considered	OpenStax
potential energy diagram	graph of a particle’s potential energy as a function of position	OpenStax
potential energy difference	negative of the work done acting between two points in space	OpenStax
renewable	energy source that is replenished by natural processes, over human time scales	OpenStax
turning point	position where the velocity of a particle, in one-dimensional motion, changes sign	OpenStax
average power	work done in a time interval divided by the time interval	OpenStax
kinetic energy	energy of motion, one-half an object’s mass times the square of its speed	OpenStax
net work	work done by all the forces acting on an object	OpenStax
power	(or instantaneous power) rate of doing work	OpenStax
work	done when a force acts on something that undergoes a displacement from one position to another	OpenStax
work done by a force	integral, from the initial position to the final position, of the dot product of the force and the infinitesimal displacement along the path over which the force acts	OpenStax
work-energy theorem	net work done on a particle is equal to the change in its kinetic energy	OpenStax
banked curve	curve in a road that is sloping in a manner that helps a vehicle negotiate the curve	OpenStax
centripetal force	any net force causing uniform circular motion	OpenStax
Coriolis force	inertial force causing the apparent deflection of moving objects when viewed in a rotating frame of reference	OpenStax
drag force	force that always opposes the motion of an object in a fluid; unlike simple friction, the drag force is proportional to some function of the velocity of the object in that fluid	OpenStax
friction	force that opposes relative motion or attempts at motion between systems in contact	OpenStax
ideal banking	sloping of a curve in a road, where the angle of the slope allows the vehicle to negotiate the curve at a certain speed without the aid of friction between the tires and the road; the net external force on the vehicle equals the horizontal centripetal force in the absence of friction	OpenStax
inertial force	force that has no physical origin	OpenStax
kinetic friction	force that opposes the motion of two systems that are in contact and moving relative to each other	OpenStax
noninertial frame of reference	accelerated frame of reference	OpenStax
static friction	force that opposes the motion of two systems that are in contact and are not moving relative to each other	OpenStax
terminal velocity	constant velocity achieved by a falling object, which occurs when the weight of the object is balanced by the upward drag force	OpenStax
dynamics	study of how forces affect the motion of objects and systems	OpenStax
external force	force acting on an object or system that originates outside of the object or system	OpenStax
force	push or pull on an object with a specific magnitude and direction; can be represented by vectors or expressed as a multiple of a standard force	OpenStax
free fall	situation in which the only force acting on an object is gravity	OpenStax
free-body diagram	sketch showing all external forces acting on an object or system; the system is represented by a single isolated point, and the forces are represented by vectors extending outward from that point	OpenStax
Hooke's law	in a spring, a restoring force proportional to and in the opposite direction of the imposed displacement	OpenStax
inertia	ability of an object to resist changes in its motion	OpenStax
inertial reference frame	reference frame moving at constant velocity relative to an inertial frame is also inertial; a reference frame accelerating relative to an inertial frame is not inertial	OpenStax
law of inertia	see Newton’s first law of motion	OpenStax
net external force	vector sum of all external forces acting on an object or system; causes a mass to accelerate	OpenStax
newton	SI unit of force; 1 N is the force needed to accelerate an object with a mass of 1 kg at a rate of 1 m/s2	OpenStax
Newton’s first law of motion	body at rest remains at rest or, if in motion, remains in motion at constant velocity unless acted on by a net external force; also known as the law of inertia	OpenStax
Newton’s second law of motion	acceleration of a system is directly proportional to and in the same direction as the net external force acting on the system and is inversely proportional to its mass	OpenStax
Newton’s third law of motion	whenever one body exerts a force on a second body, the first body experiences a force that is equal in magnitude and opposite in direction to the force that it exerts	OpenStax
normal force	force supporting the weight of an object, or a load, that is perpendicular to the surface of contact between the load and its support; the surface applies this force to an object to support the weight of the object	OpenStax
tension	pulling force that acts along a stretched flexible connector, such as a rope or cable	OpenStax
thrust	reaction force that pushes a body forward in response to a backward force	OpenStax
weight	force $\vec{w}$ due to gravity acting on an object of mass m	OpenStax
acceleration due to gravity	acceleration of an object as a result of gravity	OpenStax
average acceleration	the rate of change in velocity; the change in velocity over time	OpenStax
average speed	the total distance traveled divided by elapsed time	OpenStax
average velocity	the displacement divided by the time over which displacement occurs	OpenStax
displacement	the change in position of an object	OpenStax
distance traveled	the total length of the path traveled between two positions	OpenStax
elapsed time	the difference between the ending time and the beginning time	OpenStax
free fall	the state of movement that results from gravitational force only	OpenStax
instantaneous acceleration	acceleration at a specific point in time	OpenStax
instantaneous speed	the absolute value of the instantaneous velocity	OpenStax
instantaneous velocity	the velocity at a specific instant or time point	OpenStax
kinematics	the description of motion through properties such as position, time, velocity, and acceleration	OpenStax
position	the location of an object at a particular time	OpenStax
total displacement	the sum of individual displacements over a given time period	OpenStax
two-body pursuit problem	a kinematics problem in which the unknowns are calculated by solving the kinematic equations simultaneously for two moving objects	OpenStax
acceleration vector	instantaneous acceleration found by taking the derivative of the velocity function with respect to time in unit vector notation	OpenStax
angular frequency	$\omega$, rate of change of an angle with which an object that is moving on a circular path	OpenStax
centripetal acceleration	component of acceleration of an object moving in a circle that is directed radially inward toward the center of the circle	OpenStax
displacement vector	vector from the initial position to a final position on a trajectory of a particle	OpenStax
position vector	vector from the origin of a chosen coordinate system to the position of a particle in two- or threedimensional space	OpenStax
projectile motion	motion of an object subject only to the acceleration of gravity	OpenStax
range	maximum horizontal distance a projectile travels	OpenStax
reference frame	coordinate system in which the position, velocity, and acceleration of an object at rest or moving is measured	OpenStax
relative velocity	velocity of an object as observed from a particular reference frame, or the velocity of one reference frame with respect to another reference frame	OpenStax
tangential accleration	magnitude of which is the time rate of change of speed. Its direction is tangent to the circle.	OpenStax
time of flight	elapsed time a projectile is in the air	OpenStax
total accleration	vector sum of centripetal and tangential accelerations	OpenStax
trajectory	path of a projectile through the air	OpenStax
velocity vector	vector that gives the instantaneous speed and direction of a particle; tangent to the trajectory	OpenStax
accuracy	the degree to which a measured value agrees with an accepted reference value for that measurement	OpenStax
base quantity	physical quantity chosen by convention and practical considerations such that all other physical quantities can be expressed as algebraic combinations of them	OpenStax
base unit	standard for expressing the measurement of a base quantity within a particular system of units; defined by a particular procedure used to measure the corresponding base quantity	OpenStax
conversion factor	a ratio that expresses how many of one unit are equal to another unit	OpenStax
derived quantity	physical quantity defined using algebraic combinations of base quantities	OpenStax
derived units	units that can be calculated using algebraic combinations of the fundamental units	OpenStax
dimension	expression of the dependence of a physical quantity on the base quantities as a product of powers of symbols representing the base quantities; in general, the dimension of a quantity has the form $L^{a} M^{b} T^{c} I^{d} \Theta^{e} N^{f} J^{g}$ for some powers a, b, c, d, e, f, and g	OpenStax
dimensionally consistent	equation in which every term has the same dimensions and the arguments of any mathematical functions appearing in the equation are dimensionless	OpenStax
dimensionless	quantity with a dimension of $L^{0} M^{0} T^{0} I^{0} \Theta^{e} N^{0} J^{0}$= 1; also called quantity of dimension 1 or a pure number	OpenStax
discrepancy	the difference between the measured value and a given standard or expected value	OpenStax
English units	system of measurement used in the United States; includes units of measure such as feet, gallons, and pounds	OpenStax
estimation	using prior experience and sound physical reasoning to arrive at a rough idea of a quantity’s value; sometimes called an “order-of-magnitude approximation,” a “guesstimate,” a “back-of-the-envelope calculation”, or a “Fermi calculation”	OpenStax
kilogram	SI unit for mass, abbreviated kg	OpenStax
law	description, using concise language or a mathematical formula, of a generalized pattern in nature supported by scientific evidence and repeated experiments	OpenStax
meter	SI unit for length, abbreviated m	OpenStax
method of adding percents	the percent uncertainty in a quantity calculated by multiplication or division is the sum of the percent uncertainties in the items used to make the calculation	OpenStax
metric system	system in which values can be calculated in factors of 10	OpenStax
model	representation of something often too difficult (or impossible) to display directly	OpenStax
order of magnitude	the size of a quantity as it relates to a power of 10	OpenStax
percent uncertainty	the ratio of the uncertainty of a measurement to the measured value, expressed as a percentage	OpenStax
physical quantity	characteristic or property of an object that can be measured or calculated from other measurements	OpenStax
physics	science concerned with describing the interactions of energy, matter, space, and time; especially interested in what fundamental mechanisms underlie every phenomenon	OpenStax
precision	the degree to which repeated measurements agree with each other	OpenStax
second	the SI unit for time, abbreviated s	OpenStax
SI units	the international system of units that scientists in most countries have agreed to use; includes units such as meters, liters, and grams	OpenStax
significant figures	used to express the precision of a measuring tool used to measure a value	OpenStax
theory	testable explanation for patterns in nature supported by scientific evidence and verified multiple times by various groups of researchers	OpenStax
uncertainty	a quantitative measure of how much measured values deviate from one another	OpenStax
units	standards used for expressing and comparing measurements	OpenStax
anticommutative property	change in the order of operation introduces the minus sign	OpenStax
antiparallel vectors	two vectors with directions that differ by 180°	OpenStax
associative	terms can be grouped in any fashion	OpenStax
commutative	operations can be performed in any order	OpenStax
component form of a vector	a vector written as the vector sum of its components in terms of unit vectors	OpenStax
corkscrew right-hand rule	a rule used to determine the direction of the vector product	OpenStax
cross product	the result of the vector multiplication of vectors is a vector called a cross product; also called a vector product	OpenStax
difference of two vectors	vector sum of the first vector with the vector antiparallel to the second	OpenStax
direction angle	in a plane, an angle between the positive direction of the x-axis and the vector, measured counterclockwise from the axis to the vector	OpenStax
displacement	change in position	OpenStax
distributive	multiplication can be distributed over terms in summation	OpenStax
dot product	the result of the scalar multiplication of two vectors is a scalar called a dot product; also called a scalar product	OpenStax
equal vectors	two vectors are equal if and only if all their corresponding components are equal; alternately, two parallel vectors of equal magnitudes	OpenStax
magnitude	length of a vector	OpenStax
null vector	a vector with all its components equal to zero	OpenStax
orthogonal vectors	two vectors with directions that differ by exactly 90°, synonymous with perpendicular vectors	OpenStax
parallel vectors	two vectors with exactly the same direction angles	OpenStax
parallelogram rule	geometric construction of the vector sum in a plane	OpenStax
polar coordinate system	an orthogonal coordinate system where location in a plane is given by polar coordinates	OpenStax
polar coordinates	a radial coordinate and an angle	OpenStax
radical coordinate	distance to the origin in a polar coordinate system	OpenStax
resultant vector	vector sum of two (or more) vectors	OpenStax
scalar	a number, synonymous with a scalar quantity in physics	OpenStax
scalar component	a number that multiplies a unit vector in a vector component of a vector	OpenStax
scalar equation	equation in which the left-hand and right-hand sides are numbers	OpenStax
scalar product	the result of the scalar multiplication of two vectors is a scalar called a scalar product; also called a dot product	OpenStax
scalar quantity	quantity that can be specified completely by a single number with an appropriate physical unit	OpenStax
tail-to-head geometric construction	geometric construction for drawing the resultant vector of many vectors	OpenStax
unit vector	vector of a unit magnitude that specifies direction; has no physical unit	OpenStax
unit vectors of the axes	unit vectors that define orthogonal directions in a plane or in space	OpenStax
vector	mathematical object with magnitude and direction	OpenStax
vector components	orthogonal components of a vector; a vector is the vector sum of its vector components	OpenStax
vector equation	equation in which the left-hand and right-hand sides are vectors	OpenStax
vector product	the result of the vector multiplication of vectors is a vector called a vector product; also called a cross product	OpenStax
vector quantity	physical quantity described by a mathematical vector—that is, by specifying both its magnitude and its direction; synonymous with a vector in physics	OpenStax
vector sum	resultant of the combination of two (or more) vectors	OpenStax

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