Formula Nomenclature

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This is a glossary of standard letters and symbols to show the factors or dimensions used in formulas and tables. Numerous disciplines such as chemistry, civil, electrical, mechanical, and ect. have standards that have established.

A

Symbol	Definition	US	Metric
$a$	constant in an intensity-duration frequency curve	-	-
$a$	distance to lowest cable point	$ft$	$m$
$a$	speed	$ft/sec$	$m/s$
$a$	sound	$ft/sec$	$m/s$
$A$	angle	$degree^\circ$	$degree^\circ$
$A$	area	$ft^2$	$m^2$
$A$	area of long span structure	$ft^2$	$m^2$
$A$	area of section	-	-
$A$	atomic weight	$lbm/lbmol$	$kg/kmol$
$A$	cross-sectional area of flow in at right angles to the direction of flow	$ft^2$	$m^2$
$A$	drainage area	-	-
$A$	total surface area	-	-
$A$	width of roadway surface of roadbed in determining culvert length	-	-
$ADP$	apparatus dew point	$^\circ F$	$^\circ C$
$A_c$	partial area flow	-	-
$A_c$	axle load during construction	-	-
$A_f$	factor used to calculate the thrust due to dead load in th conduit wall	-	-
$A_r$	recurring annual amount	-	-
$A_H$	horizontal acceleration ratio due to earthquake loading, equal to the zonal acceleration ratio, dimensionless	-	-
$A_V$	velocity acceleration ratio due to earthquake loading, equal to two-thirds the horizontal acceleration ratio, $A_H$ , dimensionless	-	-

B

Symbol	Definition	US	Metric
$b$	base	-	-
$b$	bottom width of a trapezoid channel	-	-
$b$	constant in an intensity-duration frequency curve	-	-
$b$	developed width factor	-	-
$b$	dimension	$in$	$m$
$B$	volumetric fraction	-	-
$BF$	bypass factor	-	-
$Bi$	Biot number	-	-

C

Symbol	Definition	US	Metric
$c$	chord length	-	-
$c$	light (vacuum)	$ft/sec$	$m/s$
$c$	parameter of the catenary	$ft$	$m$
$c_p$	specific heat	$Btu/lbm-^\cir F$	$kJ/kg \cdot ^\circ C$
$C$	coefficient	-	-
$C$	concentration	$ppm$	$mg/L$
$C$	thermal capacitance	$Btu/^oF$	$J/K$

D

Symbol	Definition	US	Metric
$d$	distance	$ft$	$m$
$D$	diameter	$ft$	$m$

E

Symbol	Definition	US	Metric
$e$	electron	-	-
$E$	effectiveness	-	-
$E$	bulk modules	$lbf/ft^2$	$Pa$
$E$	modulas of elasticity	$lbf/ft^2$	$Pa$
$E$	voltage	$V$	$V$
$EW$	equivalent weight	$lbm/lbmol$	$kg/kmol$

F

Symbol	Definition	US	Metric
$f$	function	-	-
$f$	friction	-	-
$F$	Faraday constant	-	$C/mol$
$F$	force	$lbf$	$N$
$F$	thrust force	$lbf$	$N$
$F$	formality	-	$FW/L$
$FW$	formula weight	$lbm/lbmol$	$kg/kmol$
$F_o$	Fourier number	-	-

G

Symbol	Definition	US	Metric
$g$	earth (mean)	$ft/sec^2$	$m/s^2$
$g$	acceleration of gravity	$ft/sec^2$	$m/s^2$
$g_{c}$	gravitational constant	$lbm-ft/lbf-sec^2$	-
$G$	heat generation rate	$Btu/hr-ft^3$	$W/m^3$
$G$	gravimetric fraction	-	-

H

Symbol	Definition	US	Metric
$h$	enthalpy	$Btu/lbm$	$kJ/kg$
$h$	film coefficient	$Btu/hr-ft^2-^\circ F$	$W/m^2\cdot K$
$h$	head	$ft$	$m$
$h$	height	$ft$	$m$
$h$	Planck's constant	-	$J\cdot s$
$H$	enthalpy	$Btu/lbm$	$kJ/kg$
$H$	horizontal cable force	$lbf$	$N$
$H$	Henry's law constant	$l/atm$	$l/atm$
$HV$	heating value	$Btu/lbm$	$kJ/kg$
$HWD$	hot well depression	$^\circ F$	$^\circ C$

I

Symbol	Definition	US	Metric
$I$	current	$A$	$A$
$I$	impulse	$lbf-sec$	$N\cdot s$
$I_{sp}$	specific impulse	$sec$	$s$

J

Symbol	Definition	US	Metric
$J$	Joule's constant (778.17)	$ft-lbf/Btu$	-

K

Symbol	Definition	US	Metric
$k$	Boltzmann constant	$ft-lbf/l^\circ R$	$J/J/K$
$k$	ratio of specific heats	-	-
$k$	thermal conductivity	$Btu-ft/hr-ft^2-^\circ F$	$W/m\cdot K$

L

Symbol	Definition	US	Metric
$l$	distance	$ft$	$m$
$l$	length	$ft$	$m$

M

Symbol	Definition	US	Metric
$m$	mass	$lbm$	$kg$
$m$	molality	-	$mol/1000g$
$m_e$	electron (rest)	$lbm$	$kg$
$m_n$	nutron (rest)	$lbm$	$kg$
$m_p$	proton (rest)	$lbm$	$kg$
$m$	$\sqrt{hP/kA}$	$l/ft$	$l/m$
$M$	Mach number	-	-
$M$	molar concentration	$lbmol/ft^3$	$kmol/m^3$
$M$	molarity	-	$mol/l$
$M$	moment	$ft-lbf$	$N \cdot m$
$MC$	moisture content	$%$	$%$
$MW$	molecular weight	$lbm/lbmol$	$kg/kmol$

N

Symbol	Definition	US	Metric
$n$	number of moles	-	-
$N$	normality	-	$GEW/L$
$N$	normal force	$lbf$	$N$
$N_A$	Avagadro's number	-	$l/mol$

O

Symbol	Definition	US	Metric

P

Symbol	Definition	US	Metric
$p$	proton	-	-
$p$	pressure	$lbf/ft^2$	$kPa$
$P$	power	$W$	$W$
$P$	perimeter	$ft$	$m$
$PF$	performance factor	-	-

Q

Symbol	Definition	US	Metric
$q$	angle	$deg$	$deg$
$q$	heat per unit mass	$Btu/lbm$	$J/kg$
$q$	heat transfer per unit area	$Btu/hr-ft^2$	$W/m^2$
$Q$	heat flow rate	$Btu/sec$	$kW$
$Q$	heat transfer rate	$Btu/hr$	$W$

R

Symbol	Definition	US	Metric
$r$	radius	$ft$	$m$
$r$	empirical rate	-	-
$R$	electrical resistance	$\Omega$	$\Omega$
$R$	thermal resistance	$hr-^\circ F/Btu$	$K/W$
$R$	reaction force	$lbf$	$N$
$R$	specific gas constant	$ft-lbf/lbm-^\circ R$	$kJ/kg \cdot K$
$RF$	rating factor	-	-
$R*$	universal gas constant	$ft-lbf/lbmol-^\circ R$	$J/kmol\cdot K$
$R_cp$	critical pressure ratio	-	-

S

Symbol	Definition	US	Metric
$s$	distance along cable	$ft$	$m$
$s$	entropy	$Btu/lbm-^\circ R$	$kJ/kg\cdot K$
$S$	sag	$ft$	$m$
$S$	shape factor	$ft$	$m$
$SG$	specific gravity	-	-
$SHR$	sensible heat ratio	-	-
$S_H$	circumferential stress	$lbf/in^2$	$Pa$

T

Symbol	Definition	US	Metric
$t$	thickness	$ft$	$m$
$t$	time	$hr$	$s$
$T$	temperature	$^\circ F$	$^\circ C$
$T$	tension	$lbf$	$N$
$TDS$	total dissolved solids	$ppm$	$mg/L$
$TTD$	terminal temperature difference	$^\circ F$	$^\circ C$
$TU$	transfer units	-	-

U

Symbol	Definition	US	Metric
$u$	atomic mass unit	$lbm$	$kg$
$U$	internal energy	$Btu$	$J$
$U$	overall heat transfer coefficient	$But/hr-ft^2-^\circ F$	$W/m^2\cdot K$

V

Symbol	Definition	US	Metric
$v$	velocity	$ft/sec$	$m/s$
$V$	volume	$ft^3$	$m^3$
$VI$	viscosity index	$various$	$various$

W

Symbol	Definition	US	Metric
$w$	width	$ft$	$m$
$w$	unit weight of soil	-	$kN/m^3$
$W$	weight	$ft$	$m$
$W$	total weight of soil and live weight loads over a structure	-	-
$W$	work	$ft-lbf$	$kW$
$WS$	water surface	-	-

X

Symbol	Definition	US	Metric
$x$	distance	$ft$	$m$
$x$	gravimetric fraction	-	-
$x$	horizontal position	$ft$	$m$
$x$	mole fraction	-	-
$x$	relative ambundance	-	-
$X$	fraction ionized	-	-
$X$	horizontal position	$ft$	$m$

Y

Symbol	Definition	US	Metric
$y$	bleed friction	-	-
$y$	distance	$ft$	$m$
$y$	elevation	$ft$	$m$
$y$	vertical position	$ft$	$m$
$Y$	vertical position	$ft$	$m$

Z

Symbol	Definition	US	Metric
$z$	depth	$ft$	$m$
$z$	elevation	$ft$	$m$
$Z$	compressibility factor	-	-
$Z$	atomic number	-	-

Symbols

Symbol	Definition	US	Metric
$\large%20\alpha$	diffusivity	$ft^2/hr$	$m^2/s$
$\large%20\beta$	compressibility	$ft^2/lbf$	$Pa$
$\large%20\beta$	contact angle	$deg$	$deg$
$\large%20\gamma$	empirical constant	$1/^\circ F$	$1/K$
$\large%20\gamma$	specific weight	$lbf/ft^3$	-
$\large%20\delta$	semivertex angle	$deg$	$deg$
$\large%20\eta$	efficiency	-	-
$\large%20\epsilon$	strain	$in/in$	$m/mdeg$
$\large%20\theta$	angle	$deg$	$deg$
$\large%20\theta$	shock semivertex angle	$deg$	$deg$
$\large%20\theta$	shear strain	$rad$	$rad$
$\large%20\mu$	absolute viscosity	$lbf-sec/ft^2$	$Pa\cdot s$
$\large%20\mu$	degree of saturation	-	-
$\large%20\nu$	kinematic viscosity	$ft^2/sec$	$m^2/s$
$\large%20\pi$	osmotic pressure	$lbf/ft^2$	$Pa$
$\large%20\rho$	mass density	$lbm/ft^3$	$kg/m^3$
$\large%20\rho$	electrical resistivity	$\large%20\Omega^(-in)$	$\large%20\Omega^(-cm)$
$\large%20\sigma$	surface tension	$lbf/ft$	$N/m$
$\large%20\sigma$	normal stress	$lbf/in^2$	$Pa$
$\large%20\tau$	shear stress	$lbf/ft^2$	$Pa$
$\large%20\tau$	thermal time constant	$hr$	$s$
$\large%20\upsilon$	specific volume	$ft^3/lbm$	$m^3/kg$
$\large%20\phi$	angle	$deg$	$deg$
$\large%20\phi$	relative humidity	-	-
$\large%20\omega$	humidity ratio	$lbm/lbm$	$kg/kg$

Subscripts

Symbol	Definition
$0$	initial
$0$	total (stagnation)
$a$	ambient
$a$	dry air
$b$	base
$c$	characteristic
$c$	critical
$cp$	critical pressure
$corr$	corrected
$d$	discharge
$dp$	dew-point
$e$	exit
$e$	equivalent
$eff$	effective
$f$	formation
$f$	saturated fluid
$f$	fin
$fg$	fluid to gas (vaporization)
$fg$	vaporization
$F$	thrust
$h$	hydraulic
$i$	inlet
$i$	inner
$i$	$i$ th layer
$j$	$j$ th film
$l$	latent
$L$	per unit length
$m$	mechanical or intermediate
$o$	origional
$o$	outer
$p$	at pressure p
$p$	constant pressure
$r$	radiation
$r$	radius
$r$	reaction
$ref$	reference
$s$	sensible
$s$	surface
$sat$	saturated
$sp$	specitic
$t$	at time t
$t$	total
$th$	thermal
$T$	at temperature T
$T$	constant temperature
$v$	vapor
$v$	velocity
$w$	water
$xb$	wet-bulb
$x$	at distance x
$x$	before the shock wave
$y$	after the shock wave
$\large%20\infty$	at infinity

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Formula Nomenclature

Contents

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

Symbols

Subscripts