Previous | Top | Next

# Constants / Conversions

Contents -- Multiplier Prefixes | Misc. Constants | Speed Conversions | Distance Conversions | Acceleration Conversions | Decibels (dB)
 Constants

Decimal Multiplier Prefixes
Multiplier Power Prefix Symbol
10100 googol
1,000,000,000,000 1012 tera T trillion
1,000,000,000 109 giga G billion
1,000,000 106 mega M million
1,000 103 kilo k thousand
100 102 hecto h
10 101 deka da
0.1 10-1 deci d
0.01 10-2 centi c
0.001 10-3 milli m
0.000 001 10-6 micro µ
0.000 000 001 10-9 nano n
0.000 000 000 001 10-12 pico p
0.000 000 000 000 001 10-15 femto f
0.000 000 000 000 000 001 10-18 atto a

In the U.S. sometimes g's or a grand refers to a thousand (103).
In some (European) countries 1018 is a trillion, and 1012 is a billion.

 Speed of Light(c) in a vacuum 299,792,456.2 meters / second 983,571,050.5 feet / second 1,079,252,842 kilometers / hour 670 616 625.4 miles / hour 582,749,914.9 nautical miles / hour 299,792.4562 kilometers / second 186,282.3959 miles / second 161,874.9763 nautical miles / second 983.571 050 5 feet / microsecond 0.983 571 051 feet / nanosecond

 Approximate Speed of Sound (Mach 1) Sea Level Linear decrease to 36,000 to 82,000 feet Linear Increase to 82k to 154k feet 765 mph 660 mph 755 mph
Speed of Sound at Sea Level = 1 mi / 4.7 second.
Speed of Sound (36k-82k ft) = 1 mi / 5.5 seconds.

 Other Constants Permittivity of free space: eo = µo-1 c-2 Farads/meter eo = 8.854 185 x 10-12 F/m Permeability of free space: µo = 4(pi) x 10-7 Henrys/meter µo = 1.26 637 061 x 10-6 H/m Intrinsic Impedance of free space: Z = 376.73 ohms Acceleration due to Gravity: g = 9.80 665 m/s2 g = 32.1740 ft/s2 Boltzmann's Constant: k = 1.380 622 x 10-23 Watt*sec/°K

Transcendental Numbers
Base of Natural Logarithms (ln):
e = 2.71828 18284 59045 23536 02874 71352 66249 77572 47093 69995...

pi = 3.14159 26535 89793 23846 26433 83279 50288 41971 69399 37510...
1 radian = 180°/pi = 57.3°

Logarithm Base Conversions log10 (x) = ln (x) / ln (10) = 0.434 294 4819 ln (x)
ln (x) = log10 (x) / log10 (e) = 2.302 585 093 log10 (x)
 Typical U.S. Interstate LeftShoulder LaneWidth RightShoulder HeightClearance MaximumGrade 3 ft 12 ft 10 ft 14 ft 5% city6% mountains
Standard Railroad Gauge: 4 feet, 8.5 inches

 Conversions

SPEED
1 meter / second = 1 / 0.3048 feet / second
3.6 kilometers / hour
1 / 0.44704 miles / hour
900 / 463 nautical miles / hour

1 foot / second = 0.3048 meters / second
1.09728 kilometers / hour
15 / 22 miles / hour
274.32 / 463 nautical miles / hour

1 kilometer / hour = 1 / 3.6 meters / second
5 / 5.4864 feet / second
1 / 1.609344 miles / hour
1 / 1.852 nautical miles / hour

1 mile / hour = 0.44704 meters / second
22 / 15 feet / second
1.609344 kilometers / hour
402.336 / 463 nautical miles / hour

1 nautical mile / hour = 1 knot = 463 / 900 meters / second
463 / 274.32 feet / second
1.852 kph
463 / 402.336 miles / hour

DISTANCE
1 inch = 0.0254 meters

1 foot = 12 inches
1/ 3 yards
0.3048 meters

1 yard = 36 inches
3 feet
0.9144 meters

1 meter = 1 / 0.0254 inch
1 / 0.3048 feet
1 / 0.9144 yards

1 kilometer = 1 / 1.852 nautical miles
1 / 1.609344 miles
1 / 0.0009144 yards
1 / 0.0003048 feet
1000 meters

1 mile (statute) = 1609.344 / 1852 nautical miles
1.609344 kilometer
1760 yards
5280 feet
1609.344 meters

1 nautical mile = 1852 / 1609.344 miles
1.852 kilometers
1852 / 0.9144 yards
1852 / 0.3048 feet
1852 meters

1 nautical mile (UK) = 1853.184 meters

ACCELERATION
Exact Approximate

1 m / s2 = 1 / 0.3048 = 3.2808 ft / s2
9 / 2.5 = 3.6 kph / s
1 / 0.44704 = 2.2369 mph / s
900 / 463 = 1.9438 knots / s
1 / 9.80665 = 0.1020 g's

1 ft / s2 = 0.3048 = 0.3048 m / s2
15 / 22 = 0.6818 mph / s
1.09728 = 1.0973 kph / s
274.32 / 463 = 0.5925 knots / s
0.3048 / 9.80665 = 0.0311 g's

1 mph / s = 22 / 15 = 1.4667 ft / s2
0.44704 = 0.447 m / s2
1.609344 = 1.6093 kph / s
402.336 / 463 = 0.8690 knots / s
0.44704 / 9.80665 = 0.0456 g's

1 kph / s = 2.5 / 9 = 0.2778 m / s2
5 / 5.4864 = 0.9113 ft / s2
1 / 1.609344 = 0.6214 mph / s
1 / 1.852 = 0.54 knots / s
2.5 / (9 * 9.80665) = 0.0283 g's

1 knot / s = 463 / 900 = 0.5144 m / s2
463 / 274.32 = 1.6878 ft / s2
463 / 402.336 = 1.1508 mph / s
1.852 = 1.852 kph / s
463 / (900 * 9.80665) = 0.0525 g's

1 g = 9.80665 = 9.81 m / s2
9.80665 / 0.3048 = 32.1740 ft / s2
9.80665 [ 3600 / (5280 * 0.3048)] = 21.9369 mph / s
3.6 * 9.80665 = 35.3039 kph / s
3600 * 9.80665 / 1852 = 19.0626 knots / s

 g = 9.80665 m/s2 by International Definition ft/s2 = feet per second per second m/s2 = meters per second per second mph/s = miles per hour per second kph/s = kilometers per hour per second knots/s = nautical miles per hour per second
 Decibels (dB)

 ratio = 10dB/10 dB = 10 log(ratio) mW = 10dBm/10 dBm = 10 log(mW) W = 10dBW/10 dBW = 10 log(W) W = WattsmW = milliwatts 3 dB-3 dB = = 1.99520.5012 dB + dB = dBdBm + dB = dBmdBm + dBm = nonsense

 Range Radio Radar double (2) +6 dB +12 dB half (1/2) -6 dB -12 dB

Receiver Noise Power In = kTB Watts
 k = Boltzmann's Constant = 1.380 622 x 10-23 Watt*sec/°K T = Temperature in Degrees Kelvin (K°) B = Receiver Noise Bandwidth in Hertz (Hz)

kTB = -174 dBm/Hz
T = 300°K (80°F), B = 1 Hz

Isotropic Antenna Gain (dBi) compared to
Standard Dipole Antenna Gain (dBD)
dBi = dBD +2.15
dBD = dBi - 2.15
dBi = Gain compared to isotropic antenna.
dBD = Gain compared to dipole antenna.