Formula Symbols - R
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Formula Symbols
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R
| Symbol | Greek Symbol | Definition | English | Metric | SI | Value |
|---|---|---|---|---|---|---|
| \(L\) | - | 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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