# Formula Symbols - P

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

## Formula Symbols

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## P

SymbolGreek SymbolDefinitionEnglishMetricSIValue
$$\partial$$ partial partial derivative - - - -
$$\rho_p$$ rho particle density $$\large{\frac{lbm}{ft^3}}$$ $$\large{\frac{kg}{m^3}}$$ $$kg-m^{-3}$$  -
$$d_p$$ - particle diameter - $$nm$$ $$nm$$  -
$$m_p$$ - particle mass $$lbm$$ $$kg$$ $$kg$$  -
$$R$$, $$\;r$$ - particle position vector - - -  -
$$\Delta p$$ - Pascal's law $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$ -
$$PSD$$ - passing sight distance $$ft$$ $$m$$ $$m$$ -
$$Pe$$ - Peclet number dimensionless  -
$$N_p$$ - Peel number dimensionless  -
$$P$$ - perimeter $$ft$$ $$m$$ $$m$$  -
$$T$$ - period - - -  -
$$T$$ - periodic time - - -  -
$$PF$$ - performance factor - - -  -
$$PN$$ - performance number - - -  -
$$\mu$$ mu permeability  $$ft^2$$ $$m^2$$ $$m^2$$  -
$$k$$ - permeability coefficient $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$ -
$$\mu_o$$ mu permeability of vacuum - $$\large{\frac{H}{m}}$$ $$H-m^{-1}$$  $$1.256\;637\;062\;12\;(19)\;x\;10^{-6}$$ $$\large{\frac{H}{m}}$$
$$\epsilon$$ epsilon permittivity - $$\large{\frac{F}{m}}$$  $$H-m^{-1}$$  -
$$\epsilon_o$$ epsilon permittivity of vacuum - $$\large{\frac{F}{m}}$$  $$H-m^{-1}$$  $$8.854\;187\;8128\;(13)\;x\;10^{-12}$$ $$\large{\frac{F}{m}}$$
$$p$$ - Peng-Robinson equation of state $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$ -
$$y$$ - perpendicular distance to the neutral axis $$in$$ $$mm$$ $$mm$$ -
$$r_{\perp}$$ - perpendicular radius $$ft$$ or $$in$$ $$m$$ or $$mm$$ $$m$$ or $$mm$$  -
$$pH$$ - ph dimensionless  -
$$\gamma$$ gamma photon - - -  -
$$\pi$$ pi Pi dimensionless constant $$3.141\;592\;653 ...$$
$$C$$ - Pierce parameter dimensionless  -
$$n_{pig}$$ - pigging efficiency dimensionless -
$$d$$, $$\;d_p$$ - pipe inside diameter ID $$in$$ $$mm$$ $$mm$$  -
$$l$$, $$\;l_p$$ - pipe length $$ft$$ $$m$$ $$m$$ -
$$t$$, $$\;t_p$$ - pipe thickness $$in$$ $$mm$$ $$mm$$  -
$$W_p$$ - pipe weight $$lbf$$ $$N$$ $$kg-m-s^{-2}$$  -
$$\rho$$ rho pipeline parameter dimensionless -
$$F_p$$ - piping geometry factor dimensionless  -
$$PDV$$ - piston deck volume $$in^3$$ $$cc^3$$ $$cc^3$$  -
$$p$$ - pitch $$in$$ $$mm$$ $$mm$$ -
$$q_p$$ - Planck change $$ft$$ $$m$$ $$m$$ $$1.88\;x\;10^{-18}$$ $$m$$
$$Pl$$, $$\;h$$ - Planck constant $$\large{\frac{lbf-ft}{sec}}$$  $$J-s$$ $$kg-m^2-s^{-1}$$ $$6.626\;0693\;(11)\;x\;10^{-34}$$ $$J-s$$
$$E_p$$ - Planck energy $$lbf-ft$$ $$J$$ $$kg-m^2-s^{-2}$$ $$1.96\;x\;10^{9}$$ $$J$$
$$Y$$ - Planck function - - -  -
$$l_p$$ - Planck length $$ft$$ $$m$$ $$m$$ $$1.616\;24\;(12)\;x\;10^{-35}$$ $$m$$
$$m_p$$ - Planck mass $$lbm$$ $$kg$$ $$kg$$ $$2.176\;45\;(16)\;x\;10^{-8}$$ $$kg$$
$$T_p$$ - Planck temperature $$F$$ $$K$$ $$x-273.15\;C$$ $$1.416\;79\;(11)\;x\;10^{32}$$ $$K$$
$$t_l$$ - Planck time $$sec$$ $$s$$ $$s$$ $$5.39\;21\;(40)\;x\;10^{-44}$$ $$s$$
$$\alpha$$, $$\;\beta$$, $$\;\gamma$$, $$\;\theta$$, $$\;\phi$$ alpha, beta, gamma, theta, phi plane angle $$deg$$ $$rad$$ $$rad$$  -
$$p$$ - plasma pressure - - -  -
$$Z$$ - plastic section modulus $$in^2$$ $$mm^2$$ $$mm^2$$  -
$$b$$ - plate long side dimension $$ft$$ $$m$$ $$m$$  -
$$a$$ - plate short side dimension $$ft$$ $$m$$ $$m$$  -
$$O$$ - point of origin - - -  -
$$v$$ - Poiseuille's equation for compressible fluids $$\large{\frac{ft}{sec}}$$  $$\large{\frac{m}{s}}$$  $$m-s^{-1}$$   -
$$\mu$$ mu Poisson's ratio dimensionless  -
$$J$$ - polar moment of inertia $$in^4$$ $$mm^4$$ $$mm^4$$ -
$$J$$ - polar area moment of inertia $$in^4$$ $$mm^4$$ $$mm^4$$  -
$$e$$ - polarization vector - - -  -
$$V$$ - pollution emission rate $$\large{\frac{ft^3}{hr}}$$  $$\large{\frac{m^3}{h}}$$  $$m^3-h^{-1}$$  -
$$n$$ - polytropic exponent dimensionless  -
$$J$$ - polar moment of inertia $$in^4$$ $$m^4$$ $$m^4$$  -
$$P$$, $$\;\phi$$, $$\;n$$ phi porosity dimensionless  -
$$\phi$$ phi porous media - - -  -
$$x$$ - position - - -  -
$$x_d$$, $$\;\Delta x$$ Delta position differential - - -  -
$$U$$, $$\;V$$ - potential difference - - -  -
$$PE$$, $$\;E_p$$ - potential energy $$lbf-ft$$ $$J$$ $$kg-m^2-s^{-2}$$  -
$$E_z$$ - potential energy of a fluid at an elevation $$lbf-ft$$ $$J$$ $$kg-m^2-s^{-2}$$ -
$$P$$ - power (electric) $$\large{\frac{lbf-ft}{sec}}$$  $$W$$ $$kg-m^2-s^{-3}$$   -
$$pf$$ - power factor dimensionless  -
$$W$$ - power jack load $$lbf$$ $$N$$ $$kg-m-s^{-2}$$   -
$$N_p$$ - Power number dimensionless  -
$$PTR$$ - power-to-heat ratio dimensionless  -
$$Pr$$ - Prandtl number dimensionless  -
$$\beta$$ beta Prater number dimensionless  -
$$p$$ - pre-ignition cylinder pressure of an engion $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$ -
$$\;p$$ - pressure $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$  -
$$\phi$$ - pressure angle $$deg$$ $$rad$$ $$rad$$  -
$$C_p$$, $$\;\beta$$ beta pressure coefficient dimensionless  -
$$p_d$$, $$\;\Delta p$$ Delta pressure differential $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$  -
$$x_T$$ - pressure differential ratio factor $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$  -
$$\Delta p$$ Delta pressure drop $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$ -
$$PG$$ - pressure gradient $$\large{\frac{psi}{ft}}$$ $$\large{\frac{Pa}{m}}$$ $$Pa-m^{-1}$$   -
$$p$$ - pressure gauge $$psig$$ $$kPa$$ $$kPa$$  -
$$p_{inc}$$ - pressure increase $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$  -
$$\Delta P$$ - pressure loss $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$ -
$$\Delta P_f$$ - pressure loss due to friction $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$  -
$$p$$ - pressure of an ideal gas $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$ -
$$F_L$$ - pressure recovery factor - - -  -
$$P$$ - pressure scale - - - -
$$\alpha$$, $$\;\alpha_p$$ alpha pressure wave velocity $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$  -
$$S$$ - probability current density - - -  -
$$P$$ - probability density - - -  -
$$\propto$$ propto proportional to - - -  -
$$p$$ - proton - - -  -
proton g-factor dimensionless constant $$5.585\;694\;713$$
$$a_{gp}$$ - proton gravitational coupling constant dimensionless constant $$8.09\;x\;10^{-37}$$
$$m$$ - proton magnetic moment - - - -
$$m_p$$  - proton mass $$lbm$$ $$kg$$ $$kg$$ $$1.672\;621\;923\;69(51)\;x\;10^{-27}$$ $$kg$$
$$m_p c^2$$ - proton rest energy $$MeV$$ $$MeV$$ $$MeV$$  $$938.272\;088\;16(29)$$ $$MeV$$
$$m_p$$ - proton rest mass $$lbm$$ $$kg$$ $$kg$$ $$1.672\;621\;923\;69(51)\;x\;10^{-27}$$ $$kg$$
$$\eta$$ eta pulley efficiency - - -  -
$$\epsilon$$ epsilon pulley loss factor - - -  -
$$\eta_p$$ eta pump efficiency dimensionless -
$$PHP$$, $$HP_p$$ - pump horsepower $$\large{\frac{lbf-ft}{sec}}$$ $$\large{\frac{Btu}{s}}$$ $$Btu-s^{-1}$$  -
$$n$$ - pump speed $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$   -
Symbol Greek Symbol Definition English Metric   Value

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