# Formula Symbols - A

Written by Jerry Ratzlaff on . Posted in Nomenclature & Symbols for Engineering, Mathematics, and Science

## Formula Symbols

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

## A

SymbolGreek SymbolDefinitionUSMetricValue
$$V_d$$ - Abbe number dimensionless dimensionless  -
$$\lambda$$ lambda absolute activity - -  -
$$p_a$$ - absolute pressure $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$  -
$$\epsilon$$ epsilon absolute roughness $$in$$ $$mm$$  -
$$T_a$$ - absolute temperature $$^\circ F\;or\; ^\circ R$$ $$C \;or\; K$$  -
$$R_t$$ - absolute thermal resistance $$hr-^\circ F\;/\;Btu$$ $$K\;/\;W$$ -
$$P_c$$ - absolute thermodynamic critical pressure - -  -
$$\mu$$ mu absolute viscosity $$lbf\;/\;ft^2-sec$$ $$Pa-s$$  -
$$\alpha$$ alpha absorptance - -  -
$$\alpha$$ alpha absorptivity - -  -
$$a$$ - acceleration $$ft\;/\;sec^2$$ $$m\;/\;s^2$$  -
$$g$$   acceleration of free fall $$ft\;/\;sec^2$$ $$m\;/\;s^2$$  -
$$g$$ - acceleration of gravity $$ft\;/\;sec^2$$ $$m\;/\;s^2$$  -
$$n_a$$ - acceptor number density - -  -
$$J$$, $$\;S$$ - action integral - -  -
$$\gamma$$ gamma activity coefficient dimensionless dimensionless  -
$$E_a$$ - activation energy $$ft-lbf$$ $$J$$  -
$$ACFM$$ - actual flow rate $$cfm$$ $$L \;/\; s$$  -
$$e$$ - actual vapor pressure $$lbf\;/\;ft^2$$ $$Pa$$  -
$$l$$ - acoustic path length between tranducer faces $$ft$$ $$m$$  -
$$p$$ - acoustic pressure - -  -
$$t_d$$ - accustic signal downstream travel time $$sec$$ $$s$$  -
$$t_u$$ - accustic signal downstream travel time $$sec$$ $$s$$  -
$$A$$ - affinity - -  -
$$t$$ - age of concrete days days -
$$t_o$$ - age of concrete at loading days days -
$$t_c$$   age of concrete when drying starts at end of moist curing days days -
$$a$$ - aggregate content of concrete $$lb\;/\;yd^3$$ $$kg\;/\;m^3$$ -
$$A$$ - air - - -
$$\alpha$$ alpha air content expressed as percentage % % -
$$ACR$$ - air consumption rate $$SCFM$$ $$SCFM$$  -
$$CFM$$, $$\;Q_a$$ - air flow rate $$ft^3\;/\;min$$ $$m^3\;/\;m$$  -
$$Q_a$$ - air flow rate through piping $$ft^3\;/\;min$$ $$m^3\;/\;m$$  -
$$AFR$$ - air-fuel ratio $$lbm$$ $$kg$$  -
$$AHP$$ - air horsepower $$hp$$ -  -
$$T_i$$ - air inlet temperature -  -  -
$$m_a$$ - air mixture $$lbm$$ $$kg$$  -
$$T_o$$ - air outlet temperature  - -  -
$$p_l$$ - air pressure loss through piping $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$  -
$$F_a$$ - air resistance of drag $$lbf$$ $$N$$  -
$$F_a$$ - air resistance force $$lbf$$ $$N$$  -
$$c_a$$ - air specific heat $$Btu\;/\;lb- ^\circ F$$ $$kJ\;/\;kg-K$$  -
$$\gamma_a$$ gamma air specific weight $$lbf\;/\;ft^3$$ $$N\;/\;m^3$$  -
$$v_a$$ - air velocity $$ft\;/\;sec$$ $$m\;/\;s$$ -
$$s$$ - AGMA stress number $$lbf\;/\;in^2$$ $$Pa$$  -
$$Al$$ - Alfven number dimensionless dimensionless  -
$$v_a$$ - Alfven speed - -  -
$$A$$ - algebric difference in grade % % -
$$F_a$$ - allowable axial stress $$psi \;or\; ksi$$ $$kPa \;or\; MPa$$  -
$$F_b$$ - allowable bending stress $$psi \;or\; ksi$$ $$kPa \;or\; MPa$$  -
$$F_c$$ - allowable compressive stress $$psi \;or\; ksi$$ $$kPa \;or\; MPa$$  -
$$F_v$$ - allowable shear stress $$psi \;or\; ksi$$ $$kPa \;or\; MPa$$  -
$$S$$ - allowable stress $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$  -
$$ASD$$ - allowable stress design - - -
$$S_a$$ - allowable stress range $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$ -
$$F_t$$ - allowable tensile stress $$psi \;or\; ksi$$ $$kPa \;or\; MPa$$  -
$$A$$ - allowance - -  -
$$m_a$$ - alpha particle mass constant constant $$6.644\;655\;98\;x\;10^{-27}\;kg$$
$$AC$$ - alternating current amp -  -
$$T_a$$ - ambient temperature $$F$$ $$C$$  -
$$n$$, $$\;v^{18}$$ - amount of substance - -  -
$$I$$ - amp - -  -
$$A$$ - ampere - -  -
$$A$$ - amplitude $$ft$$ $$m$$  -
$$A$$ - amplitude $$rad$$ $$rad$$  -
$$A_l$$ - amplitude (longitudinal) constant constant $$3.662748116\;x\;10^{-19}\;m$$
$$AR$$ - amplitude ratio - -  -
$$\beta$$ beta Andrade's beta $$hr^{- \frac{1}{3}}$$ $$h^{- \frac{1}{3}}$$  -
$$A$$, $$\;B$$, $$\;C$$ - Antoine constant $$inHg$$ $$mmHG$$  -
$$A$$, $$\;\theta$$, $$\;deg$$ theta angle $$deg$$ $$rad$$  -
$$\phi$$ phi angle $$deg$$ $$rad$$  -
$$\theta$$ theta angle between acoustic path and the pipe's longitudinal axis $$deg$$ $$rad$$  -
$$\Delta A$$ delta angle differential $$deg$$ $$rad$$  -
$$\theta$$ theta angular rotation $$rpm$$ $$rad\;/\;s$$  -
$$\gamma$$ gamma angle of twist $$deg$$ $$rad$$  -
$$\alpha$$ alpha angular acceleration $$deg\;/\;sec^2$$ $$rad \;/\;s^2$$  -
$$\theta$$ theta angular deflection $$deg$$ $$rad$$  -
$$\theta$$ theta angular displacement $$deg$$ $$rad$$  -
$$\omega$$ omega angular frequency $$ft\;/\;sec$$ $$rad\;/\;s$$  -
$$H$$ - angular impulse - -  -
$$L$$ - angular momentum $$lb-ft^2\;/\;sec$$ $$kg-m^2\;/\; s$$  -
angular Planck constant constant constant $$1.054\;571\;726\;x\;10^{-34}\;kg\;m^2\;s^{-1}$$
$$\theta$$ theta angular position $$rad$$ $$rad$$  -
$$\theta$$ theta angular rotation $$rpm$$ $$rad\;/\;s$$  -
$$\omega$$ omega angular speed $$rpm$$ $$rad\;/\;s$$  -
$$\omega$$, $$\;v_a$$ omega angular velocity $$ft\;/\;sec$$ $$rad\;/\;s$$  -
$$d \omega$$, $$\;\Delta \omega$$ omega angular velocity differential $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$k$$ - angular wave number - -  -
$$k$$ - angular wave vector - -  -
$$a$$ - apothem - -  -
$$F_a$$ - applied force $$lbf$$ $$N$$  -
$$R$$ - applied stress $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$
$$Ar$$ - Archimedes number dimensionless dimensionless  -
$$E$$, $$\;V$$ - arc voltage $$volt$$ $$volt$$
$$\overset{\frown}{l}$$, $$\; l_a$$ - arc length $$in \;or\; ft$$ $$mm \;or\; m$$ -
$$A$$, $$\;S$$ - area $$in^2 \;or\; ft^2$$ $$mm^2 \;or\; m^2$$  -
$$A$$, $$\;A_c$$ - area cross-section $$in^2 \;or\; ft^2$$ $$mm^2 \;or\; m^2$$ -
$$A_{throat}$$ - area cross the throat of a weld $$in^2 \;or\; ft^2$$ $$mm^2 \;or\; m^2$$  -
$$A_d$$ - area differential - -  -
$$f_a$$ - area gradient $$ft$$ $$m$$  -
$$\Delta A$$  - area thermal expansion $$ft^2$$ $$m^2$$  -
$$\alpha_a$$ alpha area thermal expansion coefficient $$ft^2$$ $$m^2$$  -
$$Ar$$ - Arrhenius number dimensionless dimensionless  -
$$ASD$$ - allowable stress design - -  -
$$R$$ - aspect ratio - -  -
$$\rho$$ rho atmosphere density - -  -
$$p_a$$, $$\;p_{atm}$$ - atmospheric pressure $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$  -
$$m_a$$ - atomic mass - -  -
$$m_u$$ - atomic mass constant constant constant $$1.660\;539\;066\;60\;x\;10^{-27}\;kg$$
$$u$$ - atomic mass unit $$lbm$$ $$kg$$  -
$$Z$$ - atomic number dimensionless dimensionless  -
$$N$$ - atomic number density - $$atoms\;/\;cm^3$$ -
$$A$$ - atomic weight $$lbm\;/\;lbmol$$ $$kg\;/\;kmol$$  -
$$A$$ - Atwood number dimensionless dimensionless  -
$$Nv$$ - Avagadro's number - -  -
$$\Phi$$ Phi availability function $$Btu \;/\; lbm$$ $$kJ \;/\; kg$$  -
$$\bar {a}$$, $$\;a_a$$ - average acceleration $$ft\;/\;sec^2$$ $$m\;/\;s^2$$  -
$$\bar {\alpha}$$ alpha average angular acceleration $$lbf\;/\;ft^2-sec$$ $$Pa-s$$  -
$$v_a$$, $$\;\bar{\omega}$$ omega average angular velocity $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$\bar {F}$$, $$\;F_a$$ - average force $$lbf$$ $$N$$  -
$$mw$$ - average mole rate - - -
$$\bar {u}$$, $$\;v_a$$ - average speed $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$\sigma_{avg}$$ sigma average stress of weld $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$ -
$$\bar {v}$$, $$\;v_a$$ - average velocity $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$v_a$$ - averave axial velocity of water flow $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$L$$, $$\;N_a$$ - Avogadro constant constant constant $$6.022 \;140 \;76 \;x\; 10^{23} mol^{-1}$$
$$D_a$$ - axial diffusivity $$ft^2\;/\;min$$ $$m^2\;/\;s$$  -
$$P$$ - axial force $$lb \;,\; kip$$ $$N \;,\; kN$$  -
$$\epsilon_a$$, $$\;\epsilon$$ epsilon axial strain (longitudinal strain) $$ft$$ $$m$$  -
Symbol Greek Symbol Definition US Metric Value

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