• r = rad (plane angle)
• R = roentgen (radiation exposure)
• rad (radian) = rad (plane angle; base unit)
• Rad = 0.01 Gy (absorbed dose)
• radian = rad (plane angle)
• Radiance
  • radiance = W/m^2*sr (category unit)
• radiance = W/m^2*sr (radiance; category unit)
• radiant energy = energy (energy)
• radiant energy density = pressure (pressure)
• radiant exitance = heat flux density (heat flux density)
• radiant flux = power (power)
• radiant flux received = heat flux density (heat flux density)
• Radiant Intensity
  • radiant intensity = W/sr (category unit)
• radiant intensity = W/sr (radiant intensity; category unit)
• radiant power = power (power)
• Radiation Exposure
  • R = roentgen
  • roentgen = 0.000258 A*s/kg
• radiation exposure = specific charge (specific charge)
• radioactivity = frequency (frequency)
• rankine = dR (thermodynamic temperature)
• rd = rod (length)
• reactance = electric resistance (electric resistance)
• reaction rate = concentration rate (concentration rate)
• ream (of paper) = 20 quire
• reaumur = dRe (thermodynamic temperature)
• refrigeration = 12000 BTU/ton*hour (unknown units)
• register ton = 100 ft^3 (volume)
• rehoboam = 3 magnum (volume)
• Reluctance
  • reluctance = 1/H (category unit)
• reluctance = 1/H (reluctance; category unit)
• Reluctivity
  • reluctivity = 1/H*m (category unit)
• reluctivity = 1/H*m (reluctivity; category unit)
• rem = 0.01 Sv (dose equiv)
• Replaced Values
  • / = replacement for " per "
  • ^2 = replacement for "squared"
  • ^3 = replacement for "cubed"
  • ap = replacement for "apoth"
  • ap = replacement for "apothecary"
  • equiv = replacement for "equivalent"
  • fl = replacement for "liq"
  • fl = replacement for "liquid"
  • foot (" foot ") = replacement for "'"
  • foot = replacement for "feet"
  • inch (" inch ") = replacement for """
  • inch = replacement for "inches"
  • intl = replacement for "international"
  • oz = replacement for "ounce"
  • UK ("UK ") = replacement for "imp "
  • UK = replacement for "British"
  • UK = replacement for "imperial"
  • y ("y ") = replacement for "ies "
  • yr = replacement for "year"
• Replacements
  • ' = " foot "
  • " = " inch "
  • *approx = ""
  • *avg = ""
  • *exact = ""
  • apoth = "ap"
  • apothecary = "ap"
  • approx = ""
  • avdp = ""
  • avg = ""
  • avoirdupois = ""
  • British = "UK"
  • cubed = "^3"
  • equivalent = "equiv"
  • exact = ""
  • feet = "foot"
  • ies ("ies ") = "y "
  • imp ("imp ") = "UK "
  • imperial = "UK"
  • inches = "inch"
  • international = "intl"
  • liq = "fl"
  • liquid = "fl"
  • ounce = "oz"
  • per (" per ") = "/"
  • squared = "^2"
  • year = "yr"
• resistance = electric resistance (electric resistance)
• Resistivity
  • resistivity = ohm*m (category unit)
  • volume resistivity = resistivity
• resistivity = ohm*m (resistivity; category unit)
• rev = revolution (plane angle)
• revolution = 2 pi*rad (plane angle)
• reyn = lbf*s/in^2 (dynamic viscosity; derived unit)
• rhe = 10 m^2/N*s (fluidity)
• ri (Japanese ri) = 2.44 mile (length)
• rod (surveyors rod) = 25 link (length)
• roentgen = 0.000258 A*s/kg (radiation exposure)
• Roman amphora = 6.84 gallon (volume)
• Roman cubit = 17.5 in (length)
• Roman foot = 0.971 foot (length)
• Roman mile = 5000 Roman foot (length)
• Roman obolus = 8.77 grain (mass)
• Roman talent = 125 libra (mass)
• rood = 40 rod^2 (area)
• rope = 20 ft (length)
• rotational acceleration = angular acceleration (angular acceleration)
• rotational frequency = angular velocity (angular velocity)
• rpm (revolutions per minute) = revolution/minute (angular velocity; derived unit)
• rutherford = 1000000 Bq (activity)
• rydberg = 1.36054 electron volt (energy)

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