I know Einstein's famous equation E=mc2 has to do with energy, but what units are used and what do they mean?
GERALD DYCK, ASSONET, MASSACHUSETTS
Equations in physics and astronomy use the International System of Units, or SI. According to SI, the speed of light, c, is measured in meters per second, or m/s, as are all velocity measurements. Mass, m, is measured in kilograms, or kg. Energy, E, is in joules, or J. Joules are a derived SI unit, from base units kg, m, and s. The definition of a joule is kg*(m/s)2, which is not surprisingly the definition of Einstein's famous equation. In more familiar terms, a joule is the work done to produce 1 watt for 1 second.