# Formula Symbols - A

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

For other symbols see:  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

SymbolGreek SymbolDefinitionUSMetric
$$V$$ - Abbe number dimensionless number dimensionless number
$$\lambda$$ lambda absolute activity - -
$$p_a$$ - absolute pressure $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$
$$\epsilon$$ epsilon absolute roughness $$in$$ $$mm$$
$$T_a$$ - absolute temperature $$^\circ F\;or\; ^\circ R$$ $$C \;or\; K$$
$$P_c$$ - 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 - -
$$J \;or\; S$$ - action integral - -
$$\gamma$$ gamma activity coefficient dimensionless number dimensionless number
$$E_a$$ - 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 - -
$$ACR$$ - air consumption rate $$SCFM$$ $$SCFM$$
$$CFM$$ - 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 $$lbf$$ $$N$$
$$v_a$$ - air velocity $$ft\;/\;sec$$ $$m\;/\;s$$
$$s$$ - AGMA stress number $$lbf\;/\;in^2$$ $$Pa$$
$$Al$$ - Alfven number dimensionless number dimensionless number
$$v_a$$ - Alfven speed - -
$$F_a$$ - 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 $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$
$$F_t$$ - allowable tensile stress $$psi \;or\; ksi$$ $$kPa \;or\; MPa$$
$$ASD$$ - allowable stress design - -
$$A$$ - allowance - -
$$AC$$ - Alternating current amp -
$$T_a$$ - ambient temperature $$F$$ $$C$$
$$n \;or\; v^{18}$$ - amount of substance - -
$$I$$ - amp - -
$$A$$ - ampere - -
$$A$$ - amplitude $$ft$$ $$m$$
$$A$$ - amplitude $$rad$$ $$rad$$
$$AR$$ - amplitude ratio - -
$$\beta$$ beta Andrade's beta $$hr^{- \frac{1}{3}}$$ $$h^{- \frac{1}{3}}$$
$$A \;or\; B \;or\; C$$ - Antoine constant $$inHg$$ $$mmHG$$
$$A \;or\; \theta \;or\; deg$$ theta angle $$deg$$ $$rad$$
$$\phi$$ phi angle $$deg$$ $$rad$$
$$\theta$$ theta angle between acoustic path and the pipe's longitudinal axis $$deg$$ $$rad$$
$$\theta$$ theta angular deflection $$deg$$ $$rad$$
$$\Delta A$$ 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 displacement $$deg$$ $$rad$$
$$\omega$$ omega angular frequency $$ft\;/\;sec$$ $$rad\;/\;s$$
$$H$$ - angular impulse - -
$$L$$ - angular momentum $$lb-ft^2\;/\;sec$$ $$kg-m^2\;/\; s$$
$$\theta$$ theta angular position $$rad$$ $$rad$$
$$\theta$$ theta angular rotation $$rpm$$ $$rad\;/\;s$$
$$\omega$$ omega angular speed $$rpm$$ $$rad\;/\;s$$
$$\omega \;or\; v_a$$ omega angular velocity $$ft\;/\;sec$$ $$rad\;/\;s$$
$$d \omega \;or\; \Delta \omega$$ omega angular velocity differential $$ft\;/\;sec$$ $$m\;/\;s$$
$$k$$ - angular wave number - -
$$k$$ - angular wave vector - -
$$a$$ - apothem - -
$$F_a$$ - applied force $$lbf$$ $$N$$
$$Ar$$ - Archimedes number dimensionless number dimensionless number
$$A \;or\; S$$ - area $$in^2 \;or\; ft^2$$ $$mm^2 \;or\; m^2$$
$$A_{throat}$$ - 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 number dimensionless number
$$ASD$$ - allowable stress design - -
$$R$$ - aspect ratio - -
$$p_a \;or\; p_{atm}$$ - atmospheric pressure $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$
$$m_a$$ - atomic mass - -
$$m_u$$ - atomic mass constant - -
$$u$$ - atomic mass unit $$lbm$$ $$kg$$
$$Z$$ - atomic number dimensionless number dimensionless number
$$A$$ - atomic weight $$lbm\;/\;lbmol$$ $$kg\;/\;kmol$$
$$A$$ - Atwood number dimensionless number dimensionless number
$$Nv$$ - Avagadro's number - -
$$\Phi$$ Phi availability function $$Btu \;/\; lbm$$ $$kJ \;/\; kg$$
$$\bar {a} \;or\; a_a$$ - average acceleration $$ft\;/\;sec^2$$ $$m\;/\;s^2$$
$$\bar {\alpha}$$ alpha average angular acceleration $$lbf\;/\;ft^2-sec$$ $$Pa-s$$
$$v_a \;or\; \bar{\omega}$$ omega average angular velocity $$ft\;/\;sec$$ $$m\;/\;s$$
$$\bar {F} \;or\; F_a$$ - average force $$lbf$$ $$N$$
$$\bar {u} \;or\; v_a$$ - average speed $$ft\;/\;sec$$ $$m\;/\;s$$
$$\bar {v} \;or\; v_a$$ - average velocity $$ft\;/\;sec$$ $$m\;/\;s$$
$$v_a$$ - averave axial velocity of water flow $$ft\;/\;sec$$ $$m\;/\;s$$
$$D_a$$ - axial diffusivity $$ft^2\;/\;min$$ $$m^2\;/\;s$$
$$\epsilon_a$$ epsilon axial strain $$ft$$ $$m$$