Units

Memorize the following unit conversions:

  • 3.28084 ft per m
  • 2.20462 lbm per kg
  • 32.174 lbm*ft/s$^2$ per lbf
    • This is from $F = ma$
  • 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
    • 6.02214E26 (#/kmol)

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$^3$
      • Or 1000 kg/m$^3$
    • viscosity = 1.002E-3 kg/m*s
      • Or 0.001 kg/m*s
  • Air at 20$^o$C (68$^o$F) and 1 atm:
    • density = 1.204 kg/m$^3$ = 0.07518 lbm/ft$^3$.
      • O(1)
    • viscosity = 1.825E-5 kg/m*s
      • O(1E-5)
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