c | Speed of light in a vacuum, 299,792,458 m/sec |
G | Giga, a multiplier,* x109 from the Latin "gigas" (giant). In the U.S., 109 is a billion, while in other countries using SI, 1012 is a billion. Giga means 109 everywhere. |
g | Gram, a unit of mass (see SI units below) |
Hz | Hertz, the number of cycles per second |
k | Kilo, a multiplier,* x103 from the Greek "khilioi" (thousand) |
LY | Light Year, a measure of distance, the distance light travels in one year; about 63,240 AU |
M | Mega, a multiplier,* x106 from the Greek "megas" (great) |
m | Meter, a unit of length (USA spelling; elsewhere, metre) (see SI units below) |
N | Newton, a unit of force (see SI units with special names, below) |
s | Second, the SI unit of time (see this extensive definition) |
W | Watt, a unit of power (see SI units with special names, below) |