Formula Symbols - R

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

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Formula Symbols

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R

SymbolGreek SymbolDefinitionEnglishMetricSIValue
\(L\) - radiance - - -  -
\(V\) - radial displacement spherical (volume) \(in^3\) \(mm^3\) \(mm^3\)  
\(r\), \(\;\rho\) rho radial distance \(ft\) or \(in\) \(m\) or \(mm\) \(m\) or \(mm\)  -
\(Q_e\), \(\;W\) - radiant energy - - -  -
\(w\) - radiant energy density - - -  -
\(M\) - radiant exitance - - -  -
\(P\), \(\;\Phi\) Phi radiant flux - - -  -
\(\phi\) phi radiant flux density - - -  -
\(I\) - radiant intensity - - -  -
\(P\), \(\;\Phi\) Phi radiant power - - -  -
\(Q_r\) - radiant heat - - -  -
\(r\) - radius \(ft\) or \(in\) \(m\) or \(mm\) \(m\) or \(mm\)  -
\(r\) - radius of a circle \(ft\) or \(in\) \(m\) or \(mm\) \(m\) or \(mm\)  -
\(r\) - radius of a circular path \(ft\) \(m\) \(m\)  -
\(\rho\) rho radius of curvature \(in\) \(mm\) \(mm\)  -
\(R\) - radius of curvature of a beam \(ft\) \(m\) \(m\)  -
\(k\), \(\;r\) - radius of gyration \(ft\) or \(in\) \(m\) or \(mm\) \(m\) or \(mm\)  -
\(r_x\) - radius of gyration with respect to an x-axis \(in\) \(mm\) \(mm\)  -
\(r_y\) - radius of gyration with respect to an y-axis \(in\) \(mm\) \(mm\) -
\(P\) - rainfall \(in\) \(mm\) \(mm\) -
\(R\) - rainfall erosion factor - \(\large{\frac{MJ-mm}{ha-h-yr}}\) \(MJ-mm-ha^{-1}-h^{-1}-yr^{-1}\) -
\(R\) - rainfall and runoff factor - \(\large{\frac{MJ-mm}{ha-h-yr}}\) \(MJ-mm-ha^{-1}-h^{-1}-yr^{-1}\) -
\(R\) - range \(ft\) \(m\) \(m\) -
\(R\) - rankine \(R\) - - -
\(p_s\) - Raoult's law \(\large{\frac{lbf}{in^2}}\) \(Pa\)  \(kg-m^{-1}-s^{-2}\) -
\(k\) - rate coefficient - - - -
\(k\) - rate constant - \(\large{ \frac{mol}{L-s} }\) \(mol-L^{-1}-s^{-1}\) -
\(a_c\) - rate of change in acceleration \(\large{\frac{ft}{sec^3}}\) \(\large{\frac{m}{s^3}}\) \(m-s^{-3}\)  -
\(v_c\) - rate of change in velocity \(\large{\frac{ft}{sec^2}}\) \(\large{\frac{m}{s^2}}\) \(m-s^{-2}\) -
\(N\) - rate of rotation - - -  -
\(x_t\) - rated pressure drop ratio factor dimensionless  -
\(r\) - ratio - - -  -
\(\gamma\), \(\;\kappa\), \(\;k\) gamma, kappa ratio of specific heat dimensionless  -
\(F_k\) - ratio of specific heat factor dimensionless  -
\(a\) - ratio of transformation - - -  -
\(Ra\) - Rayleigh number dimensionless  -
\(\gamma\) gamma Rayleigh–Taylor instability \(\large{\frac{1}{sec}}\) \(\large{\frac{1}{s}}\) \(1-s^{-1}\) -
\(X\) - reactance - - -  -
\(R\) - reaction \(lbf\) \(N\) \(kg-m-s^{-2}\)  -
\(Q\) - reaction energy \(lbf-ft\) \(J\) \(kg-m^2-s^{-2}\)  -
\(R\) - reaction force \(lbf\) \(N\) \(kg-m-s^{-2}\)  -
\(R\) - reaction load at bearing point \(lbf\) \(N\) \(kg-m-s^{-2}\)  -
\(k\) - reaction rate constant \(\large{\frac{1}{sec}}\) \(\large{\frac{1}{s}}\) \(1-s^{-1}\) -
\(\alpha\) alpha recombination coefficient - - -  -
\(p\) - Redlich-Kwong equation of state \(\large{\frac{lbf}{in^2}}\) \(Pa\) \(kg-m^{-1}-s^{-2}\) -
\(z\) - reduced activity - - -  -
\(g'\) - reduced gravity \(\large{\frac{ft}{sec^2}}\) \(\large{\frac{m}{s^2}}\)  \(kg-m-s^{-2}\) -
\(\mu\) - reduced mass \(lbm\) \(kg\) \(kg\)  -
\(h\) = \(\frac{h}{2\;\pi}\) - reduced Plank constant - \(J-s\) \(kg-m^2-s^{-1}\) \(1.054\;571\;817...\;x\;10^{-34}\) \(J-s\)
\(p_r\) - reduced pressure \(\large{\frac{lbf}{in^2}}\) \(Pa\) \(kg-m^{-1}-s^{-2}\)  -
\(\upsilon_r\) upsilon reduced specific volume \(\large{\frac{ft^3}{lbm}}\) \(\large{\frac{m^3}{kg}}\) \(m^3-kg^{-1}\)  -
\(T_r\) - reduced temperature \( F\) \(C\) \(x+273.15\;K\)  -
\(\eta_r\), \(\;\mu_r\) eta, mu reduced viscosity \(\large{\frac{lbf - sec}{ft^2}}\) \(Pa-s\) \(kg-m^{-1}-s^{-1}\)  -
\(\rho\) rho reflectance - - -  -
\(\tau\) tau reflection coefficient - - -  -
\(\rho\) rho reflectivity - - -  -
\(RF\) - reheat factor - - -  -
\(x\) - relative abundance - - -  -
\(a\) - relative activity - - -  -
\(A_r\), \(\;M_r\) - relative atomic mass - - -  -
\(RD\), \(\;d\) - relative density dimensionless  -
\(RH\), \(\;\phi \) phi relative humidity dimensionless  -
\(M_r\) - relative molar mass - - -  -
\(\mu_r\) mu relative permeability - - -  -
\(K\) - relative permittivity - - -  -
\(\alpha\), \(\;\alpha_p\) alpha relative pressure coefficient - - -  -
\(k\) - relative roughness dimensionless  -
\(\eta_r\) eta relative viscosity \(\large{\frac{lbf - sec}{ft^2}}\) \(Pa-s\) \(kg-m^{-1}-s^{-1}\)  -
\(\eta_i\), \(\;\mu_i\) eta, mu relative viscosity increment - - -  -
\(E_r\) - relativistic energy - - -  -
\(m_r\) - relativistic mass \(lbm\) \(kg\) \(kg\)  -
\(p\) - relativistic momentum - - -  -
\(\tau\) tau relaxation time - - -  -
\(F_r\) - removal factor - - -  -
\(\rho_r\) rho residual resestivity - - -  -
\(\theta_r\) theta residual water content \(ft^3\) \(m^3\) \(m^3\) -
\(\mu\) mu resilience modulus \(\large{\frac{lbf}{in^2}}\) \(Pa\) \(kg-m^{-1}-s^{-2}\) -
\(R\), \(\;\Omega\) omega resistance (electric) \(\large{\frac{V}{I}}\) \(R\)   \(kg-m^2-s^{-3}-A^{-2}\)   -
\(K\) - resistance coefficient dimensionless  -
\(K\) - resistance coefficient for fittings and valves dimensionless  -
\(\phi\) phi resistance factor dimensionless -
\(\phi_c\) phi resistance factor for compression dimensionless  
\(\phi\) - resistinance factor for LRFD steel design - - -  -
\(\phi_c\) - resistinance factor for compression in LRFD steel design - - -  -
\(\phi_b\) - resistinance factor for flexure in LRFD steel design - - -  -
\(\phi_v\) - resistinance factor for shear in LRFD steel design - - -  -
\(\phi_t\) - resistinance factor for tension in LRFD steel design - - -  -
\(\rho\) rho resistivity - - -  -
\(R_t\) - resistors in series \(\Omega\) \(\large{\frac{kg-m^2}{s^3-A^2}}\)  \(kg-m^2-s^{-3}-A^{-2}\) -
\(R_t\) - resistors in parallel \(\Omega\) \(\large{\frac{kg-m^2}{s^3-A^2}}\)  \(kg-m^2-s^{-3}-A^{-2}\) -
\(E_0\) - rest energy \(lbf-ft\) \(J\) \(kg-m^2-s^{-2}\)  -
\(m_0\) - rest mass \(lbm\) \(kg\) \(kg\)  -
\(R\) - resultant force \(lbf\) \(N\) \(kg-m-s^{-2}\)  -
\(rpm\) - revolutions per minute \(\large{\frac{rev}{min}}\) \(\large{\frac{rev}{min}}\) \(rev-min^{-1}\)  -
\(Re\) - Reynolds number dimensionless  -
\(F_r\) - Reynolds number factor dimensionless  -
\(Re\) - Reynolds number for gas dimensionless -
\(Re\) - Reynolds number for liquid dimensionless -
\(A\) - Richardson constant - \(\large{\frac{A-m^2}{K^2}}\) \(A-m^2-K^{-2}\)  \(1.201\;73\;x\;10^6\) \(\large{\frac{A-m^2}{K^2}}\)
\(Ri\) - Richardson number dimensionless  -
\(R\) - rigidity - - -  -
\(C_{rr}\) - rolling resistance coefficient dimensionless  -
\(L_r\) - roof live load in LRFD design - - -  -
\(Ro\) - Roshko number dimensionless  -
\(Ro\) - Rossby number dimensionless  -
\(Fr_r\) - Rotating Froude number dimensionless  -
\(RHP\), \(HP_r\) - rotating horsepower \(\large{\frac{lbf-ft}{sec}}\) \(\large{\frac{Btu}{s}}\) \(J-s^{-1}\) -
\(J\), \(\;K\) - rotational \(\large{\frac{deg}{sec}}\) \(\large{\frac{rad}{s}}\) \(rad-s^{-1}\)  -
\(\alpha\) alpha rotational acceleration \(\large{\frac{deg}{sec^2}}\) \(\large{\frac{rad}{s^2}}\) \(rad-s^{-2}\)  -
\(C_r\) - rotational dampening coefficient - - -  -
\(\tau\) tau rotational force \(lbf-ft\) \(N-m\) \(N-m\)  -
\(KE_r\) - rotational kinetic energy \(lbf-ft\) \(J\) \(kg-m^2-s^{-2}\) -
\(I\) - rotarional mass moment of inertia \(lbm-ft^2\) \(kg-m^2\) \(kg-m^2\) -
\(\theta\) theta rotational motion \(deg\) \(rad\) \(rad\) -
\(n\), \(\;\omega_{cyc} \) omega rotational speed \(\large{\frac{rev}{min}}\) \(\large{\frac{rev}{min}}\) \(rev-min^{-1}\)  -
\(k_r\) - rotational spring constant - - -  -
\(k\) - rotational stiffness \(\large{\frac{lbm-ft}{deg}}\) \(\large{\frac{kg-m}{rad}}\) \(kg-m-rad^{-1}\)  -
\(F\) - rotational term - - -  -
\(\omega\) omega rotational velocity \(\large{\frac{deg}{sec}}\) \(\large{\frac{rad}{s}}\) \(rad-s^{-1}\)  -
\(W_r\) - rotational work \(lbf - ft\) \(J\) \(kg-m^2-s^{-2}\) -
\(n\) - roughness coefficient dimensionless  -
\(P\), \(\;Z\) - Rouse number dimensionless  -
\(Q\) - runoff \(ft^3\) \(m^3\) \(m^3\) -
\(CN\) - runoff curve number dimensionless -
\(R_{\infty}\) infty Rydberg constant - \(m^{-1}\) \(m^{-1}\) \(10\;973\;731.568\;160\;(21)\) \(m^{-1}\)
Symbol Greek Symbol Definition English Metric   Value

 

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