# Formula Symbols - F

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

## Formula Symbols - F

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 SymbolDefinitionUSMetricValue
$$K$$ - factor - - -
$$FS$$ - factor of safety - -  -
$$n$$ - fan speed $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$f$$ - Fanning friction factor dimensionless dimensionless  -
$$Fa$$ - Faraday constant constant constant $$96\;485.332...\;C\;mol^{-1}$$
$$k_f$$ - Fermi angular wave vector - -  -
$$G_f^0$$ - Fermi coupling constant constant constant $$1.166\;3787\;x\;10^{-5}\;GeV^{-2}$$
$$E_f$$, $$\;\epsilon_f$$ epsilon Fermi energy - -  -
$$h$$ - film coefficient $$Btu\;/\;hr-ft^2- F$$ $$W\;/\;m^2 - K$$  -
$$h$$ - film thickness $$in$$ $$mm$$  -
$$a_f$$ - final acceleration $$ft\;/\;sec^2$$ $$m\;/\;s^2$$  -
$$\omega_f$$ omega final angular velocity $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$l_f$$ - final length $$in \;or\; ft$$ $$mm \;or\; m$$  -
$$x_f$$ - final position $$in \;or\; ft$$ $$mm \;or\; m$$  -
$$T_f$$ - final temperature $$^\circ F$$ $$C$$  -
$$t_f$$ - final time $$sec$$ $$s$$  -
$$v_f$$ - final velocity $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$V_f$$ - final volume - -  -
$$\alpha$$ alpha fine structure constant dimensionless constant dimensionless constant $$7.297\;352\;5693\;x\;10^{-3}$$
$$c_1$$ - first radiation constant constant constant $$3.741\;771\;852...\;x\;10^{-16}\;W\;m^2$$
$$c_1l$$ - first radiation constant for spectral radiance constant constant $$1.191\;042\;972...\;x\;10^{-16}\;W\;m^2\;sr^{-1}$$
$$FS$$ - flash steam percent percent  -
$$T$$ - flight time $$sec$$ $$s$$  -
$$q$$ - flow $$ft^3 \;/\; sec$$ $$m^3\;/\;s$$  -
$$C_v$$, $$\;K_v$$ - flow coefficient $$lb\;/\;in^2 \;or\; psi$$  $$Pa$$   -
$$Q$$ - flow rate $$ft^3 \;/\; sec$$ $$m^3 \;/\; s$$  -
$$Q$$ - flow rate capacity $$ft^3 \;/\; sec$$ $$m^3 \;/\; s$$  -
$$Q_a$$ - flow rate of air $$CFM$$ $$LPM$$  -
$$Q_s$$ - flow rate of steam - -  -
$$Q_w$$ - flow rate of water $$gal\;/\;min$$ $$L\;/\;m$$  -
$$Q$$, $$\;V$$ - flow velocity - -  -
$$P_c$$ - fluid critical pressure $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$  -
$$\rho_f$$ rho fluid density $$lb\;/\;ft^3$$ $$kg\;/\;m^3$$  -
$$Y$$ - fluid expansion factor for vapor flow - -  -
$$h$$ - fluid head $$ft$$ $$m$$  -
$$\Delta E$$ - fluid mehanical energy loss $$ft-lbf$$ $$J$$  -
$$\xi$$ xi fluid resistance coefficient - -  -
$$P_v$$ - fluid vapor pressure $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$  -
$$v$$ - fluid velocity $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$\Delta v_f$$ - fluid velocity change $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$F$$ - force $$lbf$$ $$N$$  -
$$F_d$$, $$\;\Delta F$$ delta force differential $$lbf$$ $$N$$  -
$$F_a$$ - force of air resistance or drag $$lbf$$ $$N$$  -
$$P$$ - force of impression $$lbf$$ $$kg$$  -
$$F$$ - formality - $$FW\;/\;L$$  -
$$FW$$ - formula weight $$lbm\;/\;lbmol$$ $$kg\;/\;kmol$$  -
$$Fo$$ - Fourier number dimensionless dimensionless  -
$$g$$ - Fourier's law - - -
$$x$$ - fraction - -  -
$$f$$ - fraction split - -  -
$$d_{\infty}$$  - free steam density $$lb\;/\;ft^3$$ $$kg\;/\;m^3$$  -
$$\rho_{\infty}$$ rho  free steam pressure $$lb\;/\;in^2 \;or\; psi$$ $$Pa$$  -
$$v_{\infty}$$  - free steam velocity $$ft\;/\;sec$$ $$m\;/\;s$$  -
$$F$$ - Fresnel number dimensionless dimensionless  -
$$f$$, $$\;\nu$$ nu frequency $$Hz \;or\; ft$$ $$HZ \;or\; m$$  -
$$f$$ - friction - $$N$$  -
$$\mu$$ mu friction coefficient dimensionless dimensionless  -
$$h_fd$$   friction discharge head $$ft$$ $$m$$  -
$$f$$ - friction factor - -  -
$$F_f$$ - friction force - -  -
$$FHP$$ - friction horsepower $$hp$$ -  -
$$FP$$ - friction pressure $$in \; wg$$ $$Pa$$  -
$$h_{fs}$$   friction suction head $$ft$$ $$m$$  -
$$RA$$ - fractional reduction in area - -  -
$$F$$ - Fresnel number dimensionless dimensionless  -
$$Fo$$ - Fourier number dimensionless dimensionless  -
$$Fr$$ - Froude number dimensionless dimensionless  -
$$FAR$$ - fuel-air ratio $$lbm$$ $$kg$$  -
$$s'$$ - fuel economy $$mi\;/\;gal$$ $$km\;/\;L$$  -
$$m_f$$ - fuel mixture $$lbm$$ $$kg$$  -
$$FU$$ - fuel utilization - -  -
$$f$$ - function - -  -