Section 2 - Unit Conversions

Length

SI units -

            10 millimeters (mm) = 1 centimeters (cm)      10 centimeters = 1 decimeter (dm)

            10 decimeters = 1 meter (m)                           1000 meters = 1 kilometer (km)

            1 mm = 10-3 m                                                 1 µm = 10-6 m

            1 Angstrom = 10-10 m

Other units -

            1 km = .6214 miles                                          1 mile = 1.609 km

            1 meter = 39.37 in                                           1 in = .0254 meter

            1 mm = .03937 in                                            1 in = 25.4 mm

            12 inches = 1 foot                                            36 in = 1 yard (yd)

             5280 ft = 1 mile                                              1 cm = .3937 in = .0328 ft

            1 light year = 9.461•1015meters                       1 fathom = 6 feet

Area

SI units -

            1 cm2 = 100 mm2                                             1 m2 = 1,000,000 mm2

            1 m2 = 10,000 cm2                                           1 km2 = 1,000,000 m2

Other units -

            144 square inches (in2) = 1 square foot           43,560 ft2 = 1 arce

            1 in2 = 6.4516 cm2                                           640 arces = 1 square mile

            1 m2 = 10.76 ft2                                               1 cm2 = 0.155 in2

            1 mile2 = 640 acres = 2.590 km2

Angles

            1 radian = 57.47 degrees                                 1 quadrant = 1.571 radians

            1 degree = 60 minutes                                     100 quadrants = 90 degrees

            1 radian = .637 quadrants

Volume

SI units -

            1 cubic centimeter (cc) = 1 cm3 = 1 milliliter (ml) = 1000 mm3

            1 liter (l) = 10 cm x 10 cm x 10 cm = 1000 cm3

            1 hectoliter (hl) = 100 liters                            1 cubic meter = 1000 liters

Other units -

            1 gallon (gal) = .13368 ft3 = 3.785 liters         1 barrel (oil) = 42 gallons (oil)

            1 U.S. gallon = .8327 Imperial gallon             1 meter3 = 61023 inch3

            1 meter3 = 264.2 gallons                                 1 meter3 = 35.315 feet3

            1 meter3 = 1.308 yard3                                    1 liter = .2642 U.S. gallon                               1 liter = .0353 feet3                                         1 cm3 = .0610 inch3

            1 liter = 61.022 inch3                                     

            1 gal = 4 quarts = 8 pints = 128 fl. oz = 231 in3

Time

SI units -

            1 hour = 60 minutes = 3600 seconds               1 ms = 10-3 s

            1 µs = 10-6 s                                                    1 ns = 10-9 s

Other units -

            1 day = 24 hours = 1440 min. = 8.64 x 104 seconds

            1 year = 365.24 days = 3.156 x 107 seconds

            1 fortnight = 2 weeks

Velocity

SI units -

            1 kilometer/hour = .27778 meters/second       100 kph = 27.778 m/s

Other units -

            1 mile/hour = .447 m/s                                    60 miles/hour = 88 feet/second

            55 mph = 88.5 kph                                           60 mph = 96.54 kph

            1 radian/sec = 9.549 rpm                                65 mph = 104.6 kph

            1 foot/minute = .0183 km/hour

Mass

SI units - 

            1 gram (g) = 1000 milligrams (mg)    

            1 kilogram (kg) = 1000 grams

            1 (metric) Ton (t) = 1000 kg  

1 gram is the mass of 1 cm3 of pure water at 40C 1 kg is the mass of 1 liter of pure water.

Other units -

            1 slug = 32.2 pounds mass (lbm) = 14.59 kg

            1 kg = 6.852 x 10-2 slug

1 pound mass (lbm) weighs 1 pound force (lbf) on the Earth’s surface where the acceleration of gravity is 32.2 ft/s2 - and - 1 kg weighs 2.205 pounds force.


Force

SI units -

                        1 Newton (N) = 1 kg•m/s2

                        1 kg weighs 9.81 N on the Earth's surface where the

                                                acceleration of gravity is 9.81 m/s2

Other units -

            1 lbf = 4.4482 N                                              1 N = 0.2248 lbf

            1 kg weights 2.205 lbf                                     1 N = 105 dyne

            1 ounce = 437.5 grains = .0625 lbf

Energy 

1 calorie of heat will raise 1 gram of pure water 1°C (at 20°C)

SI units - 

            1 joule (J) = 1kg•m2/s2

            1 calorie = 4.186 J         

            1 kcal = 1000 cal = 4186 J         

Other units -

            1 Quad = 1015 Btu                                1 J = .23884 cal         

1 BTU of heat will raise 1 pound of pure water 1°F (at 39.1°F)

        1 Btu = 778.16 ft_lbf 

            1 Kilowatt•hour = 3,415.3 Btu

            1 Btu/min. = 17.57 Watts

Power

SI units -

            1 watt (W) = 1kg•m2/s3 = 1 J/s                        1 Kilowatt (kW) = 1000 W

Other units -

            1 H.P. = 550 ft•lbf/sec = 33,000 ft•lbf/min. = 745.7 W

            1 kW = 1.341 H.P. = 737.6 ft•lbf/sec              1 Btu/min = 0.02357 H.P. = 17.58 W

Temperature

Pure water freezes at 0°C and boils at 100°C at standard atmospheric pressure.

SI units -

            Kelvin (K) = Centigrade (C) + 273.16°

Other units -

     °F = (1.8 x °C) + 32°       °C = (°F - 32°) x .555

Pressure

SI units -

            1 Pascal (Pa) = 1 N/m2            1 bar = 105 N/m2

Other units -

            1 atmosphere (atm) = 101,325 Pa = 760 torr              1 lbf/in2 = 6.895 x 103 N/m2

            1 torr = 1 mm Hg = 133.32 N/m2        

            1 in H2O = 1.868 mm Hg = 249.1 N/m2

Viscosity

SI units -

            1 kg/(m_s) = 1 N_s/m2

Other units -

       1 N•s/m2 = 10 Poise

Magnetic Quantities

SI units -

            1 Tesla (T) = 1 kg/(C•s)                                  1 T = 104 Gauss (G) for B

            1 G = 1 g1/2/(cm1/2•s)                                   1 G = 103 C/(m•s) for M

            1 G = (1/4_)•103C/(m•s) for H

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