Glossary

PV diagram
a graph of pressure vs. volume
R factor
the ratio of thickness to the conductivity of a material
absolute pressure
the sum of gauge pressure and atmospheric pressure
absolute zero
the lowest possible temperature; the temperature at which all molecular motion ceases
acceleration
The rate of change in velocity; the change in velocity over time
acceleration due to gravity
acceleration of an object as a result of gravity
accuracy
the degree to which a measured value agrees with correct value for that measurement
acoustic impedance
property of medium that makes the propagation of sound waves more difficult
active transport
the process in which a living membrane expends energy to move substances across
adhesive forces
the attractive forces between molecules of different types
adiabatic process
a process in which no heat transfer takes place
air resistance
a frictional force that slows the motion of objects as they travel through the air; when solving basic physics problems, air resistance is assumed to be zero
amplitude
the maximum displacement from the equilibrium position of an object oscillating around the equilibrium position
analytical method
the method of determining the magnitude and direction of a resultant vector using the Pythagorean theorem and trigonometric identities
anecdotal evidence
information based on personal experiences or individual observations rather than controlled scientific investigation
angular acceleration
the rate of change of angular velocity with time
angular momentum
the product of moment of inertia and angular velocity
angular velocity
[latex]\omega[/latex], the rate of change of the angle with which an object moves on a circular path
antinode
the location of maximum amplitude in standing waves
approximation
an estimated value based on prior experience and reasoning
arc length
[latex]\text{Δ}s[/latex], the distance traveled by an object along a circular path
Archimedes’ principle
the buoyant force on an object equals the weight of the fluid it displaces
atmospheric pressure
The pressure exerted by the weight of the Earth's atmosphere on objects at the surface. At sea level, it averages approximately [latex]1.01 \times 10^5\ \text{Pa}[/latex] (pascals) or 1 atm.
average acceleration
the change in velocity divided by the time over which it changes
average speed
distance traveled divided by time during which motion occurs
average velocity
displacement divided by time over which displacement occurs
Avogadro’s number
[latex]{N}_{\text{A}}[/latex] , the number of molecules or atoms in one mole of a substance;
[latex]{N}_{\text{A}}=6\text{.}\text{02}×{\text{10}}^{\text{23}}[/latex] particles/mole
banked curve
the curve in a road that is sloping in a manner that helps a vehicle negotiate the curve
basal metabolic rate
the total energy conversion rate of a person at rest
beat frequency
the frequency of the amplitude fluctuations of a wave
Bernoulli’s equation
the equation resulting from applying conservation of energy to an incompressible frictionless fluid: P + 1/2pv2 + pgh = constant, through the fluid
Bernoulli’s principle
Bernoulli’s equation applied at constant depth: P1 + 1/2pv12 = P2 + 1/2pv22
bias
a systematic influence that can affect how a study is designed, conducted, measured, interpreted, or reported
blinding
a research method in which participants, researchers, or both are prevented from knowing which treatment each participant receives
blood pressure
The force per unit area exerted by circulating blood on the walls of blood vessels. In physics terms, it is a form of fluid pressure measured in units such as millimeters of mercury (mmHg). Blood pressure varies throughout the circulatory system and is typically expressed as two values: systolic pressure (when the heart contracts) and diastolic pressure (when the heart relaxes).
Boltzmann constant
[latex]k[/latex] , a physical constant that relates energy to temperature; [latex]k=\text{1.38}×{\text{10}}^{\text{–23}}\phantom{\rule{0.25em}{0ex}}\text{J/K}[/latex]
bow wake
V-shaped disturbance created when the wave source moves faster than the wave propagation speed
bulk modulus
is a measure of a material’s resistance to uniform compression. It is defined as the ratio of the infinitesimal change in pressure to the resulting relative change in volume:

[latex]B = -\frac{\Delta P}{\Delta V / V}[/latex]
where:

[latex]B[/latex] is the bulk modulus

[latex]\Delta P[/latex] is the change in pressure

[latex]\Delta V[/latex] is the change in volume

[latex]V[/latex] is the original volume

The negative sign indicates that an increase in pressure causes a decrease in volume. Materials with a high bulk modulus, like steel, are incompressible, while those with a low bulk modulus, like gases, are more compressible.

buoyant force
the net upward force on any object in any fluid
capillary action
the tendency of a fluid to be raised or lowered in a narrow tube
Carnot cycle
a cyclical process that uses only reversible processes, the adiabatic and isothermal processes
Carnot efficiency
the maximum theoretical efficiency for a heat engine
Carnot engine
a heat engine that uses a Carnot cycle
carrier particle
a fundamental particle of nature that is surrounded by a characteristic force field; photons are carrier particles of the electromagnetic force
Celsius scale
temperature scale in which the freezing point of water is [latex]\text{0º C}[/latex] and the boiling point of water is [latex]\text{100º C}[/latex]
center of gravity
the point where the total weight of the body is assumed to be concentrated
center of mass
the point where the entire mass of an object can be thought to be concentrated
centrifugal force
a fictitious force that tends to throw an object off when the object is rotating in a non-inertial frame of reference
centripetal acceleration
the acceleration of an object moving in a circle, directed toward the center
centripetal force
any net force causing uniform circular motion
change in angular velocity
the difference between final and initial values of angular velocity
change in entropy
the ratio of heat transfer to temperature [latex]Q/T[/latex]
change in momentum
the difference between the final and initial momentum; the mass times the change in velocity
chemical energy
the energy in a substance stored in the bonds between atoms and molecules that can be released in a chemical reaction
classical physics
physics that was developed from the Renaissance to the end of the 19th century
classical relativity
the study of relative velocities in situations where speeds are less than about 1% of the speed of light—that is, less than 3000 km/s
coefficient of linear expansion
[latex]\alpha[/latex], the change in length, per unit length, per [latex]1\text{º}\text{C}[/latex] change in temperature; a constant used in the calculation of linear expansion; the coefficient of linear expansion depends on the material and to some degree on the temperature of the material
coefficient of performance
for a heat pump, it is the ratio of heat transfer at the output (the hot reservoir) to the work supplied; for a refrigerator or air conditioner, it is the ratio of heat transfer from the cold reservoir to the work supplied
coefficient of volume expansion
[latex]\beta[/latex], the change in volume, per unit volume, per [latex]1\text{º}\text{C}[/latex] change in temperature
cohesive forces
the attractive forces between molecules of the same type
commutative
refers to the interchangeability of order in a function; vector addition is commutative because the order in which vectors are added together does not affect the final sum
component
a piece of a vector that points in either the vertical or the horizontal direction; every 2-d vector can be expressed as a sum of two vertical and horizontal vector components
conduction
heat transfer through stationary matter by physical contact
conservation of mechanical energy
the rule that the sum of the kinetic energies and potential energies remains constant if only conservative forces act on and within a system
conservation of momentum principle
when the net external force is zero, the total momentum of the system is conserved or constant
conservative force
a force that does the same work for any given initial and final configuration, regardless of the path followed
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
contact angle
the angle [latex]\theta[/latex] between the tangent to the liquid surface and the surface
control group
a group used for comparison with an experimental group; it does not receive the treatment being tested or may receive a placebo or standard treatment
convection
heat transfer by the macroscopic movement of fluid
conversion factor
a ratio expressing how many of one unit are equal to another unit
Coriolis force
the fictitious force causing the apparent deflection of moving objects when viewed in a rotating frame of reference
correlation
an observed relationship between two variables; correlation alone does not establish that one variable causes the other
critical damping
the 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
critical point
the temperature above which a liquid cannot exist
critical pressure
the minimum pressure needed for a liquid to exist at the critical temperature
critical temperature
the temperature above which a liquid cannot exist
cyclical process
a process in which the path returns to its original state at the end of every cycle
Dalton’s law of partial pressures
the physical law that states that the total pressure of a gas is the sum of partial pressures of the component gases
damping
The gradual loss of amplitude in an oscillating system due to energy being dissipated, typically as heat, sound, or other forms of energy. Damping reduces the system’s motion over time and can be caused by friction, air resistance, or internal material resistance.
deceleration
acceleration in the direction opposite to velocity; acceleration that results in a decrease in velocity
deformation
change in shape due to the application of force
degree Celsius
unit on the Celsius temperature scale
degree Fahrenheit
unit on the Fahrenheit temperature scale
density
the mass per unit volume of a substance or object
dependent variable
the variable that is being measured; usually plotted along the [latex]y[/latex]-axis
derived units
units that can be calculated using algebraic combinations of the fundamental units
destructive interference
when two identical waves arrive at the same point exactly out of phase; that is, precisely aligned crest to trough
dew point
the temperature at which relative humidity is 100%; the temperature at which water starts to condense out of the air
dialysis
the transport of any molecule other than water through a semipermeable membrane from a region of high concentration to one of low concentration
diastolic pressure
the minimum blood pressure in the artery
diffusion
the movement of substances due to random thermal molecular motion
direction (of a vector)
the orientation of a vector in space
displacement
the change in position of an object
distance
the magnitude of displacement between two positions
distance traveled
the total length of the path traveled between two positions
Doppler effect
an alteration in the observed frequency of a sound due to motion of either the source or the observer
Doppler shift
the actual change in frequency due to relative motion of source and observer
Doppler-shifted ultrasound
a medical technique to detect motion and determine velocity through the Doppler shift of an echo
drag force
[latex]{F}_{\text{D}}[/latex], found to be proportional to the square of the speed of the object; mathematically

[latex]{F}_{\text{D}}\propto {v}^{\text{2}}[/latex]
[latex]{F}_{\text{D}}=\frac{1}{2}\mathrm{C\rho }{\mathrm{Av}}^{2},[/latex]

where [latex]C[/latex] is the drag coefficient, [latex]A[/latex] is the area of the object facing the fluid, and [latex]\rho[/latex] is the density of the fluid

dynamic equilibrium
a state of equilibrium in which the net external force and torque on a system moving with constant velocity are zero
dynamics
the study of how forces affect the motion of objects and systems
efficiency
a measure of the effectiveness of the input of energy to do work; useful energy or work divided by the total input of energy
elapsed time
the difference between the ending time and beginning time
elastic collision
a collision that also conserves internal kinetic energy
elastic potential energy
potential energy stored as a result of deformation of an elastic object, such as the stretching of a spring
electrical energy
the energy carried by a flow of charge
emissivity
measure of how well an object radiates
energy
the ability to do work
English units
system of measurement used in the United States; includes units of measurement such as feet, gallons, and pounds
entropy
a measurement of a system's disorder and its inability to do work in a system
equation of continuity
A fundamental principle of fluid dynamics that states the mass flow rate of an incompressible fluid remains constant from one cross-section of a pipe to another. It is mathematically expressed as:
[latex]A_1v_1 = A_2v_2[/latex]
where [latex]A[/latex] is the cross-sectional area and [latex]v[/latex] is the fluid velocity. This equation shows that if the area of a pipe narrows, the fluid speed increases, and vice versa, assuming the fluid is incompressible and there is no accumulation of fluid.
evidence-based medicine
the practice of making healthcare decisions using the best available scientific evidence together with clinical expertise and the values and needs of the patient
external force
a force acting on an object or system that originates outside of the object or system
Fahrenheit scale
temperature scale in which the freezing point of water is [latex]\text{32º F}[/latex] and the boiling point of water is [latex]\text{212º F}[/latex]
fictitious force
a force having no physical origin
first law of thermodynamics
states that the change in internal energy of a system equals the net heat transfer into the system minus the net work done by the system
flow rate
abbreviated Q, it is the volume V that flows past a particular point during a time t, or Q = V/t
fluid dynamics
the physics of fluids in motion
fluids
liquids and gases; a fluid is a state of matter that yields to shearing forces
force
a push or pull on an object with a specific magnitude and direction; can be represented by vectors; can be expressed as a multiple of a standard force
force constant
a constant related to the rigidity of a system: the larger the force constant, the more rigid the system; the force constant is represented by k
force field
a region in which a test particle will experience a force
fossil fuels
oil, natural gas, and coal
free-body diagram
a sketch showing all of the external forces acting on an object or system; the system is represented by a dot, and the forces are represented by vectors extending outward from the dot
free-fall
the state of movement that results from gravitational force only
frequency
number of events per unit of time
friction
a force past each other of objects that are touching; examples include rough surfaces and air resistance
fundamental
the lowest-frequency resonance
fundamental frequency
the lowest frequency of a periodic waveform
fundamental units
units that can only be expressed relative to the procedure used to measure them
gauge pressure
the pressure relative to atmospheric pressure
gauge pressures
The pressure of a system above atmospheric pressure. It is calculated as the difference between the absolute pressure and atmospheric pressure, and is the pressure typically measured by instruments like tire gauges and blood pressure cuffs. In equation form:

[latex]P_{\text{gauge}} = P_{\text{absolute}} - P_{\text{atm}}[/latex]
Gauge pressure can be positive (above atmospheric pressure) or negative (below atmospheric pressure, also called vacuum pressure).

glaucoma
condition caused by the buildup of fluid pressure in the eye
gravitational constant, G
a proportionality factor used in the equation for Newton’s universal law of gravitation; it is a universal constant—that is, it is thought to be the same everywhere in the universe
gravitational potential energy
the energy an object has due to its position in a gravitational field
greenhouse effect
warming of the Earth that is due to gases such as carbon dioxide and methane that absorb infrared radiation from the Earth’s surface and reradiate it in all directions, thus sending a fraction of it back toward the surface of the Earth
harmonics
the term used to refer collectively to the fundamental and its overtones
head (of a vector)
the end point of a vector; the location of the tip of the vector’s arrowhead; also referred to as the “tip”
head-to-tail method
a method of adding vectors in which the tail of each vector is placed at the head of the previous vector
hearing
the perception of sound
heat
the spontaneous transfer of energy due to a temperature difference
heat engine
a machine that uses heat transfer to do work
heat of sublimation
the energy required to change a substance from the solid phase to the vapor phase
heat pump
a machine that generates heat transfer from cold to hot
Hooke’s law
proportional relationship between the force [latex]F[/latex] on a material and the deformation [latex]\Delta L[/latex] it causes, tensile strength the breaking stress that will cause permanent deformation or fraction of a material
horsepower
an older non-SI unit of power, with [latex]\text{1 hp}=\text{746 W}[/latex]
human metabolism
conversion of food into heat transfer, work, and stored fat
ideal angle
the angle at which a car can turn safely on a steep curve, which is in proportion to the ideal speed
ideal banking
the 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
ideal gas law
the physical law that relates the pressure and volume of a gas to the number of gas molecules or number of moles of gas and the temperature of the gas
ideal speed
the maximum safe speed at which a vehicle can turn on a curve without the aid of friction between the tire and the road
impulse
the average net external force times the time it acts; equal to the change in momentum
incompressible fluids
Fluids whose density does not change significantly when pressure is applied. In many physics problems, liquids such as water are treated as incompressible to simplify calculations, meaning their volume remains essentially constant under pressure. This approximation is useful in analyzing fluid dynamics, such as flow through pipes or the cardiovascular system.
independent variable
the variable that the dependent variable is measured with respect to; usually plotted along the [latex]x[/latex]-axis
inelastic collision
a collision in which internal kinetic energy is not conserved
inertia
the tendency of an object to remain at rest or remain in motion
inertial frame of reference
a coordinate system that is not accelerating; all forces acting in an inertial frame of reference are real forces, as opposed to fictitious forces that are observed due to an accelerating frame of reference
infrasound
sounds below 20 Hz
instantaneous acceleration
acceleration at a specific point in time
instantaneous speed
magnitude of the instantaneous velocity
instantaneous velocity
velocity at a specific instant, or the average velocity over an infinitesimal time interval
intensity
power per unit area
intensity reflection coefficient
a measure of the ratio of the intensity of the wave reflected off a boundary between two media relative to the intensity of the incident wave
internal energy
the sum of the kinetic and potential energies of a system’s atoms and molecules
internal kinetic energy
the sum of the kinetic energies of the objects in a system
intraocular pressure
fluid pressure in the eye
irreversible process
any process that depends on path direction
isobaric process
constant-pressure process in which a gas does work
isochoric process
a constant-volume process
isolated system
a system in which the net external force is zero
isothermal process
a constant-temperature process
joule
SI unit of work and energy, equal to one newton-meter
Kelvin scale
temperature scale in which 0 K is the lowest possible temperature, representing absolute zero
kilocalorie
[latex]\phantom{\rule{0.25em}{0ex}}1\phantom{\rule{0.25em}{0ex}}\text{kilocalorie}\phantom{\rule{0.25em}{0ex}}\text{=}\phantom{\rule{0.25em}{0ex}}\text{1000}\phantom{\rule{0.25em}{0ex}}\text{calories}[/latex]
kilogram
the SI unit for mass, abbreviated (kg)
kilowatt-hour
[latex](\text{kW}\cdot h)[/latex] unit used primarily for electrical energy provided by electric utility companies
kinematics
the study of motion without considering its causes
kinematics of rotational motion
describes the relationships among rotation angle, angular velocity, angular acceleration, and time
kinetic energy
the energy an object has by reason of its motion, equal to [latex]\frac{1}{2}{\text{mv}}^{2}[/latex] for the translational (i.e., non-rotational) motion of an object of mass [latex]m[/latex] moving at speed [latex]v[/latex]
kinetic friction
a force that opposes the motion of two systems that are in contact and moving relative to one another
laminar
a type of fluid flow in which layers do not mix
latent heat coefficient
a physical constant equal to the amount of heat transferred for every 1 kg of a substance during the change in phase of the substance
law
a description, using concise language or a mathematical formula, a generalized pattern in nature that is supported by scientific evidence and repeated experiments
law of conservation of angular momentum
angular momentum is conserved, i.e., the initial angular momentum is equal to the final angular momentum when no external torque is applied to the system
law of conservation of energy
the general law that total energy is constant in any process; energy may change in form or be transferred from one system to another, but the total remains the same
law of inertia
see Newton’s first law of motion
linear momentum
the product of mass and velocity
liter
a unit of volume, equal to 10−3 m3
longitudinal wave
a wave in which the disturbance is parallel to the direction of propagation
loudness
the perception of sound intensity
macrostate
an overall property of a system
magnitude (of a vector)
the length or size of a vector; magnitude is a scalar quantity
magnitude of kinetic friction
[latex]{f}_{k}={\mu }_{k}N[/latex], where [latex]{\mu }_{k}[/latex] is the coefficient of kinetic friction
magnitude of static friction
[latex]{f}_{s}\le {\mu }_{s}\phantom{\rule{0.25em}{0ex}}N[/latex], where [latex]{\mu }_{s}[/latex] is the coefficient of static friction and [latex]N[/latex] is the magnitude of the normal force
mass
the quantity of matter in a substance; measured in kilograms
mechanical advantage
the ratio of output to input forces for any simple machine
mechanical energy
the sum of kinetic energy and potential energy
mechanical equivalent of heat
the work needed to produce the same effects as heat transfer
metabolic rate
the rate at which the body uses food energy to sustain life and to do different activities
meter
the SI unit for length, abbreviated (m)
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
metric system
a system in which values can be calculated in factors of 10
microgravity
an environment in which the apparent net acceleration of a body is small compared with that produced by Earth at its surface
microstate
each sequence within a larger macrostate
micturition reflex
stimulates the feeling of needing to urinate, triggered by bladder pressure
model
representation of something that is often too difficult (or impossible) to display directly
modern physics
the study of relativity, quantum mechanics, or both
mole
the quantity of a substance whose mass (in grams) is equal to its molecular mass
moment of inertia
mass times the square of perpendicular distance from the rotation axis; for a point mass, it is [latex]I={\text{mr}}^{2}[/latex] and, because any object can be built up from a collection of point masses, this relationship is the basis for all other moments of inertia
motion
displacement of an object as a function of time
MRI
(Magnetic Resonance Imaging) – A noninvasive medical imaging technique that uses strong magnetic fields and radio waves to produce detailed images of the internal structures of the body. MRI is particularly effective for visualizing soft tissues, such as the brain, muscles, and organs, without using ionizing radiation.
natural frequency
the frequency at which a system would oscillate if there were no driving and no damping forces
net external force
the vector sum of all external forces acting on an object or system; causes a mass to accelerate
net rate of heat transfer by radiation
is
[latex]\frac{{Q}_{\text{net}}}{t}=\sigma eA\left({T}_{2}^{4}-{T}_{1}^{4}\right)[/latex]
net work
work done by the net force, or vector sum of all the forces, acting on an object
neutral equilibrium
a state of equilibrium that is independent of a system’s displacements from its original position
Newton’s first law of motion
a body at rest remains at rest, or, if in motion, remains in motion at a constant velocity unless acted on by a net external force; also known as the law of inertia
Newton’s second law of motion
the net external force [latex]{\mathbf{\text{F}}}_{\text{net}}[/latex] on an object with mass [latex]m[/latex] is proportional to and in the same direction as the acceleration of the object, [latex]\mathbf{\text{a}}[/latex], and inversely proportional to the mass; defined mathematically as [latex]\mathbf{\text{a}}=\frac{{\mathbf{\text{F}}}_{\text{net}}}{m}[/latex]
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 the first body exerts
Newton’s universal law of gravitation
every particle in the universe attracts every other particle with a force along a line joining them; the force is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
node
point of zero displacement
nodes
the points where the string does not move; more generally, nodes are where the wave disturbance is zero in a standing wave
non-inertial frame of reference
an accelerated frame of reference
nonconservative force
a force whose work depends on the path followed between the given initial and final configurations
normal force
the force that a surface applies to an object to support the weight of the object; acts perpendicular to the surface on which the object rests
note
basic unit of music with specific names, combined to generate tunes
nuclear energy
energy released by changes within atomic nuclei, such as the fusion of two light nuclei or the fission of a heavy nucleus
optic nerve
A bundle of over one million nerve fibers that transmits visual information from the retina to the brain. In a physics or biomedical context, damage to the optic nerve—such as from increased intraocular pressure in glaucoma—illustrates how mechanical forces (like pressure) can affect neural function and signal transmission.
order of magnitude
refers to the size of a quantity as it relates to a power of 10
oscillate
moving back and forth regularly between two points
osmosis
the transport of water through a semipermeable membrane from a region of high concentration to one of low concentration
osmotic pressure
the back pressure which stops the osmotic process if one solution is pure water
Otto cycle
a thermodynamic cycle, consisting of a pair of adiabatic processes and a pair of isochoric processes, that converts heat into work, e.g., the four-stroke engine cycle of intake, compression, ignition, and exhaust
over damping
the 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
overtones
multiples of the fundamental frequency of a sound
partial pressure
the pressure a gas would create if it occupied the total volume of space available
Pascal’s Principle
a change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container
peer review
the evaluation of scientific work by independent experts before or after publication
percent relative humidity
the ratio of vapor density to saturation vapor density
percent uncertainty
the ratio of the uncertainty of a measurement to the measured value, expressed as a percentage
perfectly inelastic collision
a collision in which the colliding objects stick together
period
time it takes to complete one oscillation
periodic motion
motion that repeats itself at regular time intervals
perpendicular lever arm
the shortest distance from the pivot point to the line along which [latex]\mathbf{\text{F}}[/latex] lies
phase diagram
a graph of pressure vs. temperature of a particular substance, showing at which pressures and temperatures the three phases of the substance occur
phon
the numerical unit of loudness
physical quantity
a characteristic or property of an object that can be measured or calculated from other measurements
physics
the science concerned with describing the interactions of energy, matter, space, and time; it is especially interested in what fundamental mechanisms underlie every phenomenon
pit
a tiny indentation on the spiral track moulded into the top of the polycarbonate layer of CD
pitch
the perception of the frequency of a sound
placebo
an inactive treatment designed to resemble the treatment being tested and used as a comparison in some clinical studies
point masses
structureless particles with no rotation or spin
Poiseuille’s law
the rate of laminar flow of an incompressible fluid in a tube: Q = (P2 − P1)πr4/8ηl
Poiseuille’s law for resistance
the resistance to laminar flow of an incompressible fluid in a tube: R = 8ηl/πr4
position
the location of an object at a particular time
potential energy
energy due to position, shape, or configuration
potential energy of a spring
the stored energy of a spring as a function of its displacement; when Hooke’s law applies, it is given by the expression [latex]\frac{1}{2}{\text{kx}}^{2}[/latex] where [latex]x[/latex] is the distance the spring is compressed or extended and [latex]k[/latex] is the spring constant
power
the rate at which work is done
precision
the degree to which repeated measurements agree with each other
pressure
the force per unit area perpendicular to the force, over which the force acts
projectile
an object that travels through the air and experiences only acceleration due to gravity
projectile motion
the motion of an object that is subject only to the acceleration of gravity
pseudoscience
claims, explanations, or practices presented as scientific that do not follow the methods and standards used to test scientific ideas
quantum mechanics
the study of objects smaller than can be seen with a microscope
quark
fundamental constituent of matter and an elementary particle
radians
a unit of angle measurement
radiant energy
the energy carried by electromagnetic waves
radiation
heat transfer which occurs when microwaves, infrared radiation, visible light, or other electromagnetic radiation is emitted or absorbed
radius of curvature
radius of a circular path
randomized controlled trial
an experiment in which participants are assigned randomly to treatment and comparison groups to reduce bias and evaluate the effect of an intervention
range
the maximum horizontal distance that a projectile travels
rate of conductive heat transfer
rate of heat transfer from one material to another
relative humidity
the amount of water in the air relative to the maximum amount the air can hold
relative osmotic pressure
the back pressure which stops the osmotic process if neither solution is pure water
relative velocity
the velocity of an object as observed from a particular reference frame
relativity
the study of objects moving at speeds greater than about 1% of the speed of light, or of objects being affected by a strong gravitational field
renewable forms of energy
those sources that cannot be used up, such as water, wind, solar, and biomass
reproducibility
the ability to obtain consistent results when scientific data, methods, or analyses are examined or repeated
resonance
the phenomenon of driving a system with a frequency equal to the system's natural frequency
resonate
a system being driven at its natural frequency
restoring force
force acting in opposition to the force caused by a deformation
resultant
the sum of two or more vectors
resultant vector
the vector sum of two or more vectors
reverse dialysis
the process that occurs when back pressure is sufficient to reverse the normal direction of dialysis through membranes
reverse osmosis
the process that occurs when back pressure is sufficient to reverse the normal direction of osmosis through membranes
reversible process
a process in which both the heat engine system and the external environment theoretically can be returned to their original states
Reynolds number
a dimensionless parameter that can reveal whether a particular flow is laminar or turbulent
right-hand rule
direction of angular velocity ω and angular momentum L in which the thumb of your right hand points when you curl your fingers in the direction of the disk’s rotation
rotation angle
the ratio of the arc length to the radius of curvature on a circular path:

[latex]\text{Δ}\theta =\frac{\text{Δ}s}{r}[/latex]

rotational inertia
resistance to change of rotation. The more rotational inertia an object has, the harder it is to rotate
rotational kinetic energy
the kinetic energy due to the rotation of an object. This is part of its total kinetic energy
saturation
the condition of 100% relative humidity
scalar
A quantity that is described by magnitude, but not direction
scientific consensus
a conclusion supported by a substantial body of evidence and accepted by most specialists working in the relevant scientific field
scientific evidence
observations and measurements obtained through systematic investigation that can be examined and evaluated by others
scientific method
a method that typically begins with an observation and question that the scientist will research; next, the scientist typically performs some research about the topic and then devises a hypothesis; then, the scientist will test the hypothesis by performing an experiment; finally, the scientist analyzes the results of the experiment and draws a conclusion
second
the SI unit for time, abbreviated (s)
second law of motion
physical law that states that the net external force equals the change in momentum of a system divided by the time over which it changes
second law of thermodynamics
heat transfer flows from a hotter to a cooler object, never the reverse, and some heat energy in any process is lost to available work in a cyclical process
second law of thermodynamics stated in terms of entropy
the total entropy of a system either increases or remains constant; it never decreases
semipermeable
a type of membrane that allows only certain small molecules to pass through
shear deformation
deformation perpendicular to the original length of an object
SI units
the international system of units that scientists in most countries have agreed to use; includes units such as meters, liters, and grams
SI units of torque
newton times meters, usually written as N·m
significant figures
express the precision of a measuring tool used to measure a value
simple harmonic motion
the oscillatory motion in a system where the net force can be described by Hooke’s law
simple harmonic oscillator
a device that implements Hooke’s law, such as a mass that is attached to a spring, with the other end of the spring being connected to a rigid support such as a wall
simple pendulum
an object with a small mass suspended from a light wire or string
slope
the difference in [latex]y[/latex]-value (the rise) divided by the difference in [latex]x[/latex]-value (the run) of two points on a straight line
sonic boom
a constructive interference of sound created by an object moving faster than sound
sound
a disturbance of matter that is transmitted from its source outward
sound intensity level
a unitless quantity telling you the level of the sound relative to a fixed standard
sound pressure level
the ratio of the pressure amplitude to a reference pressure
specific gravity
the ratio of the density of an object to a fluid (usually water)
specific heat
the amount of heat necessary to change the temperature of 1.00 kg of a substance by 1.00 ºC
Speed
The rate at which an object travels, equal to the distance traveled divided by the time taken. Speed is a scalar quantity, meaning it has magnitude only and no direction. In SI units, speed is measured in meters per second (m/s).

Mathematically,

Speed = Distance / Time

stable equilibrium
a system, when displaced, experiences a net force or torque in a direction opposite to the direction of the displacement
static equilibrium
a state of equilibrium in which the net external force and torque acting on a system is zero
static friction
a force that opposes the motion of two systems that are in contact and are not moving relative to one another
statistical analysis
using statistics to examine data, such as counting microstates and macrostates
Stefan-Boltzmann law of radiation
[latex]\frac{Q}{t}=\sigma eA{T}^{4},[/latex] where [latex]\sigma[/latex] is the Stefan-Boltzmann constant, [latex]A[/latex] is the surface area of the object, [latex]T[/latex] is the absolute temperature, and [latex]e[/latex] is the emissivity
Stokes’ law
[latex]{F}_{s}=6\mathrm{\pi r\eta v}[/latex], where
[latex]r[/latex] is the radius of the object,
[latex]\eta[/latex] is the viscosity of the fluid, and
[latex]v[/latex] is the object’s velocity
strain
ratio of change in length to original length
stress
ratio of force to area
sublimation
the phase change from solid to gas
superposition
the phenomenon that occurs when two or more waves arrive at the same point
surface tension
the cohesive forces between molecules which cause the surface of a liquid to contract to the smallest possible surface area
system
defined by the boundaries of an object or collection of objects being observed; all forces originating from outside of the system are considered external forces
systolic pressure
the maximum blood pressure in the artery
tail
the start point of a vector; opposite to the head or tip of the arrow
tangential acceleration
the acceleration in a direction tangent to the circle at the point of interest in circular motion
temperature
the quantity measured by a thermometer
tension
the pulling force that acts along a medium, especially a stretched flexible connector, such as a rope or cable; when a rope supports the weight of an object, the force on the object due to the rope is called a tension force
terminal speed
the speed at which the viscous drag of an object falling in a viscous fluid is equal to the other forces acting on the object (such as gravity), so that the acceleration of the object is zero
testable hypothesis
a proposed explanation that makes predictions that can be investigated through observation or experimentation
theory
an explanation for patterns in nature that is supported by scientific evidence and verified multiple times by various groups of researchers
thermal conductivity
the property of a material’s ability to conduct heat
thermal energy
the energy within an object due to the random motion of its atoms and molecules that accounts for the object's temperature
thermal equilibrium
the condition in which heat no longer flows between two objects that are in contact; the two objects have the same temperature
thermal expansion
the change in size or volume of an object with change in temperature
thermal stress
stress caused by thermal expansion or contraction
thrust
a reaction force that pushes a body forward in response to a backward force; rockets, airplanes, and cars are pushed forward by a thrust reaction force
timbre
number and relative intensity of multiple sound frequencies
time
change, or the interval over which change occurs
tone
number and relative intensity of multiple sound frequencies
torque
turning or twisting effectiveness of a force
trajectory
the path of a projectile through the air
transverse wave
a wave in which the disturbance is perpendicular to the direction of propagation
triple point
the pressure and temperature at which a substance exists in equilibrium as a solid, liquid, and gas
turbulence
fluid flow in which layers mix together via eddies and swirls
ultracentrifuge
a centrifuge optimized for spinning a rotor at very high speeds
ultrasound
sounds above 20,000 Hz
uncertainty
a quantitative measure of how much your measured values deviate from a standard or expected value
under damping
the condition in which damping of an oscillator causes it to return to equilibrium with the amplitude gradually decreasing to zero; system returns to equilibrium faster but overshoots and crosses the equilibrium position one or more times
uniform circular motion
the motion of an object in a circular path at constant speed
units
a standard used for expressing and comparing measurements
unstable equilibrium
a system, when displaced, experiences a net force or torque in the same direction as the displacement from equilibrium
useful work
work done on an external system
vapor
a gas at a temperature below the boiling temperature
vapor pressure
the pressure at which a gas coexists with its solid or liquid phase
vector
A quantity that is described by both magnitude and direction
vector addition
the rules that apply to adding vectors together
velocity
speed in a given direction
vibrations
Repetitive back-and-forth or oscillatory motion of an object about an equilibrium position, often caused by a restoring force. Vibrations can occur in solids, liquids, or gases, and may produce waves such as sound.
viscosity
the friction in a fluid, defined in terms of the friction between layers
viscous drag
a resistance force exerted on a moving object, with a nontrivial dependence on velocity
watt
(W) SI unit of power, with [latex]\text{1 W}=\text{1 J/s}[/latex]
wave
a disturbance that moves from its source and carries energy
wave interference
The phenomenon that occurs when two or more waves meet at the same point in space, combining to form a new wave pattern. Interference can be constructive (waves reinforce each other, increasing amplitude) or destructive (waves partially or completely cancel each other, reducing amplitude)
wave velocity
the speed at which the disturbance moves. Also called the propagation velocity or propagation speed
wavelength
the distance between adjacent identical parts of a wave
weight
the force [latex]\mathbf{\text{w}}[/latex] due to gravity acting on an object of mass [latex]m[/latex]; defined mathematically as: [latex]\mathbf{\text{w}}=m\mathbf{\text{g}}[/latex], where [latex]\mathbf{\text{g}}[/latex] is the magnitude and direction of the acceleration due to gravity
work
the transfer of energy by a force that causes an object to be displaced; the product of the component of the force in the direction of the displacement and the magnitude of the displacement
work done on an external system
work done on an external system
work-energy theorem
the result, based on Newton’s laws, that the net work done on an object is equal to its change in kinetic energy
y-intercept
the [latex]y\text{-}[/latex]value when [latex]x[/latex]= 0, or when the graph crosses the [latex]y[/latex]-axis
zeroth law of thermodynamics
law that states that if two objects are in thermal equilibrium, and a third object is in thermal equilibrium with one of those objects, it is also in thermal equilibrium with the other object

License

Icon for the Creative Commons Attribution 4.0 International License

Introductory Physics for the Health and Life Sciences I Copyright © 2012 by OSCRiceUniversity is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

Share This Book