Negative frequency Negative frequency The concept of negative and positive frequency can be as simple as a wheel rotating one way or the other way: a "signed value" of frequency can indicate both the rate and direction of rotation. The rate is expressed in units such as revolutions (a.k.a. "cycles") per second (hertz) or radian/second (where 1 cycle corresponds to 2"π" radians). Let "ω" be a nonnegative parameter with units of radians/sec. Then the angular function (angle vs. time) , has slope −"ω", which is called a negative frequency. But when the function is used as the argument of a cosine operator,
Gal (unit) Gal (unit) The gal (symbol: Gal), sometimes called galileo after Galileo Galilei, is a unit of acceleration used extensively in the science of gravimetry. The gal is defined as 1 centimeter per second squared (1 cm/s). The milligal (mGal) and microgal (µGal) refer respectively to one thousandth and one millionth of a gal. The gal is not part of the International System of Units (known by its French-language initials "SI"). In 1978 the CIPM decided that it was permissible to use the gal "with the SI until the CIPM considers that [its] use is no longer necessary". However, use of