E: Some Useful Conversion Factors

Abstract

Physical quantity Symbol SI to English conversion English to SI conversion Length L 1 m = 3.2808 ft 1 ft = 0.3048 m Area A 1 m 2 = 10.7639 ft 2 1 ft 2 = 0.092903 m 2 Volume V 1 m 3 = 35.3134 ft 3 1 ft 3 = 0.028317 m 3 Velocity v 1 m/s = 3.2808 ft/s 1 ft/s = 0.3048 m/s Density ρ 1 kg/m 3 = 0.06243 lb m /ft 3 1 lb m /ft 3 = 16.018 kg/m 3 Force F 1 N = 0.2248 lb f 1 lb f = 4.4482 N Mass m 1 kg = 2.20462 lb m 1 lb m = 0.45359237 kg Pressure p 1 N/m 2 = 1.45038 × 10 −4 lb f /in 2 1 lb f /in 2 = 6894.76 N/m 2 Energy, heat q 1 kJ = 0.94783 Btu 1 Btu = 1.05504 kJ Heat flow q 1 W = 3.4121 Btu/h 1 Btu/h = 0.29307 W Heat flux per unit area q/A 1 W/m 2 = 0.317 Btu/h · ft 2 1 Btu/h · ft 2 = 3.154 W/m 2 Heat flux per unit length q/L 1 W/m = 1.0403 Btu/h · ft 1 Btu/h · ft = 0.9613 W/m Heat generation per unit volume ˙ q 1 W/m 3 = 0.096623 Btu/h · ft 3 1 Btu/h · ft 3 = 10.35 W/m 3 Energy per unit mass q/m 1 kJ/kg = 0.4299 Btu/lb m 1 Btu/lb m = 2.326 kJ/kg Specific heat c 1 kJ/kg · • C = 0.23884 Btu/lb m · • F 1 Btu/lb m · • F = 4.1869 kJ/kg · • C Thermal conductivity k 1 W/m · • C = 0.5778 Btu/h · ft · • F 1 Btu/h · ft · • F = 1.7307 W/m · • C Convection heat-transfer coefficient h 1 W/m 2 · • C = 0.1761 Btu/h · ft 2 · • F 1 Btu/h · ft 2 · • F = 5.6782 W/m 2 · • C Dynamic 1 kg/m · s = 0.672 lb m /ft · s Viscosity μ = 2419.2 lb m /ft · h 1 lb m /ft · s = 1.4881 kg/m · s Kinematic viscosity and thermal diffusivity ν, α 1 m 2 /s = 10.7639 ft 2 /s 1 ft 2 /s = 0.092903 m 2 /s Important physical constants Avogadro's number N 0 = 6.022045 × 10 26 molecules/kg mol Universal gas constant R = 1545.35 ft · lbf/lbm · mol · • R = 8314.41 J/kg mol · K = 1.986 Btu/lbm · mol · • R = 1.986 kcal/kg mol · K Planck's constant h = 6.626176 × 10 −34 J · sec Boltzmann's constant k = 1.380662 × 10 −23 J/molecule · K = 8.6173 × 10 −5 eV/molecule · K Speed of light in vacuum c = 2.997925 × 10 8 m/s Standard gravitational acceleration g = 32.174 ft/s 2 = 9.80665 m/s 2 Electron mass m e = 9.1095 × 10 −31 kg Charge on the electron e = 1.602189 × 10 −19 C Stefan-Boltzmann constant σ = 0.1714 × 10 −8 Btu/hr · ft 2 · R 4 = 5.669 × 10 −8 W/m 2 · K 4 1 atm = 14.69595 lbf/in 2 = 760 mmHg at 32 • F = 29.92 inHg at 32 • F = 2116.21 lbf/ft 2 = 1.01325 × 10 5 N/m 2