# Useful Constants, Conversions, Prefixes, and Equations

**Common Length Unit Conversions**

1 meter = 3.281 feet

1 mile = 5,280 feet

1 mile = 1,609 meters

1 foot = 12 inches

1 inch = 2.540 cm

1 yard = 91.44 cm

1 light year (ly) = 9.461 * 10^{15} m

**Common Time Unit Conversions**

1 min = 60 s

1 hour = 60 min

1 day = 24 hours

1 week = 7 days

1 fortnight = 2 weeks

1 year = 365.24 days

1 century = 100 years

**Common Mass Unit Conversions**

1 kg = 1000 g

1 kg = 2.205 lbs on Earth’s surface

1 amu = 1.661 * 10^{-27} kg

1 oz = 0.0625 lbs

**Common Volume Unit Conversions**

1 liter = 10^{-3} m^{3}

1 gallon = 3.788 liters

1 fl oz = 29.57 ml

1000 ml = 1 liter

**Common Force Unit Conversions **

1 N = 0.2248 lbs on Earth’s surface

1 N = 10^{5} dyne

**Common Energy Unit Conversions**

1 Joule = 10^{7} ergs

1 cal = 4.186 J

1 Btu = 1055 J

1 eV = 1.602 * 10^{-19 }J

1 kWh = 3.600 * 10^{6} J

**Common Angular Unit Conversions**

1 radian (rad) = 57.30 degrees

1 rad = 180/pi degrees

1 rev = 2 * pi rad

**Common Power Unit Conversions**

1 W = 1 J/s

1 hp = 746 W

1 Btu/h = 0.293 W

**Common Pressure Unit Conversions**

1 Pa = 1 N/m^{2}

1 Pa = 1.450 * 10^{-4} lb/in^{2}

1 bar = 10^{5} Pa

1 atm = 1.013 * 10^{5} Pa

1 mm Hg = 133.3 Pa

1 torr = 133.3 Pa

# Scientific Notation Prefixes

1 P (Penta-) = 10^{15}

1 T (Tera-) = 10^{12}

1 G (Giga-) = 10^{9}

1 M (Mega-) = 10^{6}

1 k (kilo-) = 10^{3}

1 c (centi-) = 10^{-2}

1 m (milli0-) = 10^{-3}

1 (micro-) = 10^{-6}

1 n (nano-) = 10^{-9}

1 p (pico-) = 10^{-12}

# Common Physical Constants

Speed of light in a vacuum *c *= 2.99792458 * 10^{8} m/s

Gravitational Constant *G *= 6.67428 * 10^{-11 }Nm^{2}/kg^{2}

Planck’s Constant *h** = *6.62606896 * 10^{-34 }J s

Boltzmann Constant *k* = 1.3806504 * 10^{-23} J/K

Avogadro’s Number *N _{A}* = 6.02214179 * 10

^{23}molecules / mole

# Common Formulas for Area and Volume