Formula Symbols - R

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

See Dimensionless Numbers, General Constants

SymbolGreek SymbolDefinitionUSMetric
\(L\) - radiance - -
\(r \;or\; \rho\) rho radial distance \(in\;or\;ft\) \(mm\;or\;m\)
\(Q_e \;or\; W\) - radiant energy - -
\(w\) - radiant energy density - -
\(M\) - radiant exitance - -
\(P \;or\; \Phi\) Phi radiant flux - -
\(\phi\) phi radiant flux density - -
\(I\) - radiant intensity - -
\(P \;or\; \Phi\) Phi radiant power - -
\(Q_r\) - radiant heat - -
\(r\) - radius \(in\;or\;ft\) \(mm\;or\;m\)
\(r\) - radius of a circle \(in\;or\;ft\) \(mm\;or\;m\)
\(r\) - radius of a circular path \(ft\) \(m\)
\(\rho\) rho radius of curvature \(in\) \(mm\)
\(R\) - radius of curvature of a beam \(ft\) \(m\)
\(k \;or\; r\) - radius of gyration \(in\;or\;ft\) \(mm\;or\;m\)
\(r_x\) - radius of gyration with respect to an x-axis \(in\) \(mm\)
\(r_y\) - radius of gyration with respect to an y-axis \(in\) \(mm\)
\(R\) - range \(ft\) \(m\)
\(k\) - rate coefficient - -
\(a_c\) - rate of change in acceleration \(ft \;/\; sec^2\) \(m \;/\; s^2\)
\(r\) - ratio - -
\(k\) - ratio of specific heat - -
\(a\) - ratio of transformation - -
\(Ra\) - Rayleigh number dimensionless number dimensionless number
\(X\) - reactance - -
\(R\) - reaction \(lbf\) \(N\)
\(Q\) - reaction energy - -
\(R\) - reaction force \(lbf\) \(N\)
\(R\) - reaction load at bearing point \(lbf\) \(N\)
\(\alpha\) alpha recombination coefficient - -
\(z\) - reduced activity - -
\(\mu\) - reduced mass - -
\(p_r\) - reduced pressure - -
\(\upsilon_r\) upsilon reduced specific volume - -
\(T_r\) - reduced temperature - -
\(\eta_r\) eta reduced viscosity - -
\(\rho\) rho reflectance - -
\(\tau\) tau reflection coefficient - -
\(\rho\) rho reflectivity - -
\(RF\) - reheat factor - -
\(x\) - relative abundance - -
\(a\) - relative activity - -
\(A_r \;or\; M_r\) - relative atomic mass - -
\(RD \;or\; d\) - relative density dimensionless number dimensionless number
\(RH \;or\; \phi \) phi relative humidity \(^\circ F\) \(C\)
\(M_r\) - relative molar mass - -
\(\mu_r\) mu relative permeability - -
\(K\) - relative permittivity - -
\(\alpha \;or\; \alpha_p\) alpha relative pressure coefficient - -
\(k\) - relative roughness \(in\) \(mm\)
\(\eta_r\) eta relative viscosity - -
\(E_r\) - relativistic energy - -
\(m_r\) - relativistic mass \(lbm\) \(kg\)
\(p\) - relativistic momentum - -
\(\tau\) tau relaxation time - -
\(F_r\) - removal factor - -
\(\rho_r\) rho residual resestivity - -
\(R \;or\; \Omega\) omega resistance \(ohm\) \(ohm\)
\(K\) - resistance coefficient - -
\(\phi\) - 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 - -
\(R\) - resultant force \(lbf\) \(N\)
\(Re\) - Reynolds number dimensionless number dimensionless number
\(F_R\) - Reynolds number factor - -
\(A\) - Richardson constant - -
\(Ri\) - Richardson number dimensionless number dimensionless number
\(R\) - rigidity - -
\(C_{rr}\) - rolling resistance dimensionless number dimensionless number
\(L_r\) - roof live load in LRFD design - -
\(Ro\) - Roshko number dimensionless number dimensionless number
\(Ro\) - Rossby number dimensionless number dimensionless number
\(J \;or\; K\) - rotational - -
\(\alpha\) alpha rotational acceleration \(rad \;/\; sec^2\) \(rad \;/\; s^2\)
\(C_r\) - rotational dampening coefficient \(lbf-ft-sec \;/\; rad\) \(N-m-s \;/\; rad\)
\(\tau\) tau rotational force \(lbf-ft\) \(N-m\)
\(n \;or\; \omega_{cyc} \) omega rotational speed \(rpm\) \(rad\;/\;s\)
\(k_r\) - rotational spring constant \(lbf-ft \;/\; rad\) \(N-m \;/\; rad\)
\(F\) - rotational term - -
\(\omega\) omega rotational velocity \(rad \;/\; sec\) \(rad \;/\; s\)
\(R_{\infty}\) infty Rydberg constant constant constant