Units¶
Memorize the following unit conversions:
- 3.28084 ft per m
- 2.20462 lbm per kg
- 32.174 lbm*ft/s$^2$ per lbf
- 1055.056 J per Btu
- 25037 lbm*ft$^2$/s$^2$ per Btu
- 4.184 J per cal
- 101325 Pa per atm
- 0$^o$C = 273.15 K
- 0$^o$F = 459.67$^o$R
- 1$^o$C = 9/5$^o$F
- $^o$C = ($^o$F - 32)*5/9
- $^o$F = $^o$C*9/5 + 32
Also, remember these:
- 5280 ft per mile
- 12 in per foot
- 60 s per min
- 3600 s per hr
- 0$^o$C = 32$^o$F
- 1 cal is the energy to raise 1 g 1$^o$C (or K)
- 1 Btu is the energy to raise 1 lbm 1$^o$F (or R)
Memorize these constants:
- g
- 9.80665 m/s$^2$
- 32.174 ft/s$^2$
- R$_{gas}$
- 8314.46 J/kmol*K
- 1985.88 cal/kmol*K
- 1.98588 Btu/lbmol*R
- 10.73157 ft$^3$*psi/R*lbmol
- 49720 lbm*ft$^2$/s$^2$*R*lbmol
- Na
Memorize these unit equivalences (written for SI, but similar for English units).
- N = kg*m/s$^2$
- Pa = kg/m*s$^2$
- J = kg*m$^2$/s$^2$
- density = kg/m$^3$
- viscosity = kg/m*s
- kinematic viscosity, thermal diffusivity, mass diffusivity = m$^2$/s
Memorize these properties
- Liquid water at 20$^o$C (68$^o$F) and 1 atm:
- density = 998 kg/m$^3$ = 62.3 lbm/ft$^3$
- viscosity = 1.002E-3 kg/m*s
- Air at 20$^o$C (68$^o$F) and 1 atm:
- density = 1.204 kg/m$^3$ = 0.07518 lbm/ft$^3$.
- viscosity = 1.825E-5 kg/m*s