# Formula Symbols - F

on . Posted in Nomenclature & Symbols for Engineering, Mathematics, and Science

## Formula Symbols

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## F

SymbolGreek SymbolDefinitionEnglishMetricSIValue
$$K$$ - factor - - - -
$$FS$$, $$\;FOS$$ - factor of safety dimensionless  -
$$F$$, $$\;T_F$$ - Fahrenheit $$F$$ -  - -
$$\eta_f$$ eta fan efficiency dimensionless -
$$FHP$$, $$\;HP_f$$ - fan horsepower $$\large{\frac{lbf-ft}{sec}}$$ $$\large{\frac{Btu}{s}}$$ $$Btu-s^{-1}$$  -
$$n$$ - fan speed $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$  -
$$f$$ - Fanning friction factor dimensionless  -
$$Fa$$ - Faraday constant - $$\large{\frac{C}{mol}}$$ $$C-mol^{-1}$$  $$96\;485.332\;12...$$ $$\large{\frac{C}{mol^{-1}}}$$
- - Faraday's law of induction - - - -
$$k_f$$ - Fermi angular wavevector - - -  -
$$G_f$$ - Fermi coupling constant $$\large{\frac{lbf-ft}{ft^3}}$$ $$\large{\frac{J}{m^3}}$$ $$J-m^{-3}$$ $$1.435\;x\;10^{-36}$$ $$J-m^{-3}$$
$$E_f$$ - Fermi energy $$lbf-ft$$ $$J$$ $$kg-m^2-s^{-2}$$  -
$$f_f$$ - Fermi force $$lbf$$ $$N$$ $$kg-m-s^{-2}$$ -
$$p_f$$ - Fermi momentum $$\large{\frac{lbm-ft}{sec}}$$ $$\large{\frac{kg-m}{s}}$$ $$kg-m-s^{-1}$$ -
$$r_f$$ - Fermi repulsion - - - -
$$v_f$$ - Fermi velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$ -
$$h$$ - film coefficient $$\large{\frac{Btu}{ft^2-hr-F}}$$ $$\large{\frac{W}{m^2-K}}$$ $$W-m^{-2}-K^{-1}$$  -
$$h$$ - film thickness $$in$$ $$mm$$ $$mm$$   -
$$a_f$$ - final acceleration $$\large{\frac{ft}{sec^2}}$$ $$\large{\frac{m}{s^2}}$$ $$m-s^{-2}$$  -
$$\omega_f$$ omega final angular velocity $$\large{\frac{rad}{sec}}$$ $$\large{\frac{rad}{s}}$$ $$rad-s^{-1}$$  -
$$l_f$$ - final length $$ft$$ or $$in$$ $$m$$ or $$mm$$ $$m$$ or $$mm$$   -
$$x_f$$ - final position $$ft$$ or $$in$$ $$m$$ or $$mm$$ $$m$$ or $$mm$$   -
$$T_f$$ - final temperature $$F$$ $$C$$ $$x+273.15\;K$$  -
$$t_f$$ - final time $$sec$$ $$s$$ $$s$$   -
$$v_f$$ - final velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$  -
$$V_f$$ - final volume $$ft^3$$ or $$in^3$$ $$m^3$$ or $$mm^3$$  $$m^3$$ or $$mm^3$$  -
$$\alpha$$ alpha fine structure constant dimensionless constant $$7.297\;352\;5693\;x\;10^{-3}$$
$$\Delta U$$ - first law of thermodynamics  - - - -
$$Q$$ - first moment of area $$in^4$$ $$mm^4$$ $$mm^4$$  -
$$c_1$$ - first radiation constant - $$\large{\frac{W}{m^2}}$$ $$W-m^{-2}$$  $$3.741\;771\;852...\;x\;10^{-16}$$ $$\large{\frac{W}{m^2}}$$
$$FEM$$ - fixed end moment $$lbf-in$$ $$N-mm$$ $$N-mm$$ -
$$t_f$$ - flange thickness $$in$$ $$mm$$ $$mm$$
$$FS$$ - flash steam $$\large{\frac{lbf}{in^2}}$$ $$\large{\frac{kg}{mm^2}}$$ $$kg-mm^{-2}$$   -
$$T$$ - flight time $$hr$$ $$hr$$ -  -
$$q$$ - flow $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$ $$m^3-s^{-1}$$  -
$$C_v$$, $$\;K_v$$ - flow coefficient dimensionless  -
$$Q$$ - flow rate $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$ $$m^3-s^{-1}$$  -
$$Q$$ - flow rate capacity $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$ $$m^3-s^{-1}$$  -
$$Q_a$$ - flow rate of air $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$ $$m^3-s^{-1}$$  -
$$Q_s$$ - flow rate of steam $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$ $$m^3-s^{-1}$$  -
$$Q_w$$ - flow rate of water $$\large{\frac{ft^3}{sec}}$$ $$\large{\frac{m^3}{s}}$$ $$m^3-s^{-1}$$  -
$$Q$$, $$\;V$$ - flow velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$  -
$$P_c$$ - fluid critical pressure $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$   -
$$\rho_f$$ rho fluid density $$\large{\frac{lbm}{ft^3}}$$ $$\large{\frac{kg}{m^3}}$$ $$kg-m^{-3}$$  -
$$p$$ - fluid pressure at depth $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$  -
$$h$$ - fluid head $$ft$$ $$m$$ $$m$$  -
$$\Delta E$$ - fluid mehanical energy loss $$lbf-ft$$ $$J$$ $$kg-m^2-s^{-2}$$   -
$$p$$ - fluid pressure $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$  -
$$p$$ - fluid pressure at depth $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$
$$\xi$$ xi fluid resistance coefficient dimensionless  -
$$P_v$$ - fluid vapor pressure $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$   -
$$v$$ - fluid velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$  -
$$\Delta v_f$$ - fluid velocity change $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$  -
$$F$$ - force $$lbf$$ $$N$$ $$kg-m-s^{-2}$$   -
$$F_d$$, $$\;\Delta F$$ delta force differential $$lbf$$ $$N$$ $$kg-m-s^{-2}$$   -
$$F$$ - force exerted by contracting or stretching a material $$lbf$$ $$N$$  $$kg-m-s^{-2}$$ -
$$F_a$$ - force of air resistance or drag $$lbf$$ $$N$$ $$kg-m-s^{-2}$$   -
$$P$$ - force of impression $$lbf$$ $$N$$ $$kg-m-s^{-2}$$   -
$$F$$ - formality - - -  -
$$FW$$ - formula weight $$lbf$$ $$N$$ $$kg-m-s^{-2}$$   -
$$Fo$$ - Fourier number dimensionless  -
$$g$$ - Fourier's law - - - -
$$x$$ - fraction - - -  -
$$M$$ - fraction moisture dimensionless -
$$d_{\infty}$$  - free steam density $$\large{\frac{lbm}{ft^3}}$$ $$\large{\frac{kg}{m^3}}$$  $$kg-m^{-3}$$  -
$$\rho_{\infty}$$ rho  free steam pressure $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$  -
$$v_{\infty}$$  - free steam velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$  -
$$F$$ - Fresnel number dimensionless  -
$$f$$, $$\;\nu$$ nu frequency $$Hz$$ $$Hz$$  $$s^{-1}$$   -
$$Q$$ - fresh air introduction rate - - - -
$$f$$ - friction $$lbf$$ $$N$$ $$kg-m-s^{-2}$$  -
$$\mu$$ mu friction coefficient dimensionless  -
$$h_fd$$   friction discharge head $$ft$$ $$m$$ $$m$$  -
$$f$$ - friction factor dimensionless  -
$$F_f$$ - friction force - - -  -
$$FHP$$ - friction horsepower $$hp$$ $$hp$$ $$watt$$  -
$$FL$$ - friction loss $$lbf$$ $$N$$ $$kg-m-s^{-2}$$ -
$$\xi$$, $$\;C$$ xi friction loss coefficient dimensionless -
$$FP$$ - friction pressure - - -  -
$$f$$ - fraction split dimensionless -
$$h_{fs}$$   friction suction head - - -  -
$$RA$$ - fractional reduction in area $$ft^2$$ or $$in^2$$ $$m^2$$ or $$mm^2$$  $$m^2$$ or $$mm^2$$  -
$$F$$ - Fresnel number dimensionless  -
$$Fo$$ - Fourier number dimensionless  -
$$Fr$$ - Froude number dimensionless  -
$$FAR$$ - fuel-air ratio - - -  -
$$s'$$ - fuel economy $$\large{\frac{mi}{gal}}$$ $$\large{\frac{km}{L}}$$ $$km-L^{-1}$$  -
$$m_f$$ - fuel mixture - - -  -
$$FU$$ - fuel utilization - - -  -
$$f$$ - function - - -  -
Symbol Greek Symbol Definition English Metric   Value

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