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CONVERSIONS, PHYSICAL CONSTANTS, AND UNITS

Length:

1 inch (in) = 2.54 centimeters (cm) exactly

1 foot (ft) = 0.305 meters (m)

1 yard (yd) = 0.914 meters (m)1 mile (mi) = 5280 feet (ft) = 1.61 kilometers (km)

1 centimeter (cm) = 0.394 inches (in)

1 meter (m) = 100 centimeters (cm) = 39.4 inches (in) = 3.28 feet (ft) = 1.09 yards

(yd)

1 kilometer (km) = 1000 meters (m) = 0.621 miles (mi)

1 rod = 16.5 feet (ft) = 5.5 yards (yd) = 5.03 meters (m)

1 astronomical unit (AU) = 1.50 x 108 kilometers (km) = 9.29 x 107 miles (mi)

1 light year (LY) = 9.461 x 1012 kilometers ( km) = 5.88 x 1012 miles (mi) = 0.307

 parsec

1 parsec = approximately 3.26 light years (LY)

Area = length x width

1 square inch (in2) = 0.00694 square feet (ft2  = 6.45 square centimeters, cm2 

1 square foot, (ft2) = 144 square inches (in2  = 0.0929 square meters, m2 

1 square yard (yd2  = 1296 square inches (in2  = 9 square feet (ft2  = 0.836 square

meters (m2 

1 square mile (mi2  = 640 acres = 2.59 square kilometers (km2 

1 acre = 160 square rods = 43,560 square feet (ft2) = 0.405 hectares

1 hectare = 10,000 square meters (m2  = 100 ares = 2.47 acres

1 square rod = 30,25 square yards (yd2  = 25.29 square meters (m2 

1 are = 100 square meters (m2  = 0.01 hetares = 119.6 square yards (yd2 

Volume = length x width x height

1 cubic inch (in3) = 0.000579 cubic feet (ft3) = 16.4 cubic centimeters (cm3)

1 cubic foot (ft3) = 1728 cubic inch (in3) = 0.0283 cubic meters (m3)

1 cubic yard (yd3) = 27 cubic feet (ft3) = 4.65 x 104 cubic inch (in3) = 0.765 cubic

meters (m3)

1 cubic meters (m3) = 106 cubic centimeters (cm3) = 1,000 liters (L) = 35.3 cubic

feet (ft3)

1 quart (qt) = 2 pints (pt) = 946 milliliters (mL) = 0.946 liters (L)

1 gallon (gal) = 4 quarts = 231 cubic inch (in3) = 3.79 liters (L)

1 liter (L) = 1000 cubic centimeters (cm3) = 1.06 quarts (qt) = 0.265 gallons (gal)

Mass

1 slug = 14.6 kilograms (kg)

1 kilogram (kg) = 1,000 grams = 0.0685 slugs

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1 atomic mass unit (u)  = 1.66 x 10-27 kilogram (kg) =1.66 x 10-24 

1 electron mass = 9.11 x 10-31 kilogram (kg) = 9.11 x 10-28 grams (g) = 5.46 x 10-

4 atomic mass unit (u)

1 proton mass = 1.00728 atomic mass unit (u)

1 neutron mass = 1.00866 atomic mass unit (u)

Conversion Between Weight and Mass on Earth

A slug is the mass unit in the British system and is equal to 32.2 pounds (lb)

A kilogram weighs 9.81 newtons (N) or 2.21 pounds (lb)

A mass of one (1) gram (g) weighs 981 dynes or 0.0353 ounces (oz)

A one (1) ounce weight has a mass 28.4 grams (g) or 0.0284 kilograms (kg)

A one (1) pound weight has a mass of 454 grams (g) or 0.454 kilograms (kg)

A metric ton has a mass of 1,000 kilograms (kg)

A one (1) ton (regular) weight has a mass of 2,000 pounds (lb)

Velocity and Speed = distance/time1 ft/s (ft s-1) = 0.305 m/s (m s-1)

1 mi/hr (mi hr -1) = 1.47 ft/s (ft s-1) = 1.61 km/hr (km hr -1) = 0.447 m/s (m s-1)

1 m/s (m s-1) = 100 cm/s (cm s-1) = 3.28 ft/s (ft s-1)

1 km/hr (km hr -1) = 0.278 m/s (m s-1) = 0.621 mi/hr (mi hr -1) = 0.912 ft/s (ft s-1)

Speed of light in a vacuum = 3.00 x 108 m/s (m s-1) = 3.00 x 1010 cm/s (cm s-1) =

186,000 mi/s (mi s-1)

Speed of sound in air at 0 oC (32 oF) = 331 m/s (m s-1) = 1090 ft/s (ft s-1) = 41 mi/hr

(mi hr -1)

Acceleration = velocity / time

1 ft/s2  = 0.305 m/s2  = 30.5 cm/s2 

1 mi/hr/s = 1.47 ft/s2 = 1.61 km/hr/s = 0.447 m/s2 

1 m/s2 = 100 cm/s2 = 3.28 ft/s2 

Acceleration due to gravity on Earth = 9.81 m/s2  = 981 cm/s2  = 32.2 ft/s2 

Force = mass x acceleration

1 lb = 16 oz = 4.45 newtons (N)

1 N (kg· m/s2) = 0.223 lb

TemperatureoF = 9/5 x oC + 32oC = (oF - 32) x 5/9

Absolute Temperature, kelvin, K = oC + 273.15

0 K = -273.15 oC = -459.72 oF

 Normal Body Temperature = 98.6 oF

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Pressure = Force/Area

1 Pascal, Pa = 1 N/m2  = 1.45 x 10-4 lb/in2 

1 bar = 105 N/m2  = 14.50 lb/in2 

1 atmosphere, atm = 760 mm Hg = 76.0 cm Hg = 760 torr = 14.50 lb/in2  =

1.01325 x 105 N/m2 (or Pa)

Air pressure at sea level is approximately = 1 atm = 1 bar = 105 N/m2  (or Pa) =14.50 lb/in2 

Water pressure increases 9810 N/m2  for each meter of depth or 0.433 lb/in2 for each

foot of depth

Work and Energy or Heat Work = Force x parallel distance

1 joule, J = 0.738 ft . lb = 107 ergs

1 calorie, cal = 4.18 J = 0.00442 British Thermal Units, Btu

1 foot pound, ft . lb = 1.36 J

1 Btu = 252 cal = 778 ft·lb = 1.054 x 103 J

1 electron Volt, eV = 1.602 x 10-19 J

931.5 million electron volts,MeV is equivalent to 1 atomic mass unit, u 

Power = Work/time

1 horse power, hp = 550 ft·lb/s = 0.746 kilowatts, kW = 746 W

1 Watt, W = 1 J/s = 0.738 ft·lb/s = 0.00134 hp

1 Btu/hr = 0.293 W

1 kW = 1.34 hp

Radioactivity

1 curie = 3.70 x 1010 disintegrations/second = 3.70 x 1010 bequerels

SI BASE UNITSPhysical Quantity Name of Unit Symbol

Length meter m

Mass kilogram kgTime second s

Temperature kelvin K

Electric current ampere A

Luminousintensity

candela cd

Amount of

substancemole mol

SI PREFIXES

MACRO MICRO

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Factor Prefix Symbol Factor Prefix Symbol

10 exa E 10-

  deci d

10 peta P 10-

  centi c10 tera T 10

-  milli m

10 giga G 10-

  micro μ 

10 mega M 10

-

  nano n10 kilo k 10-

  pico p10 hecto h 10

-  femto f

10 deka da 10-

  atto a