chapter  1
26 Pages

## Physical concepts

WithStanley A. Gelfand

Physical quantities may be thought of as being basic or derived, and as either scalars or vectors. The basic quantities of concern are time, length (distance), and mass. The derived quantities are the results of various combinations of the basic quantities (and other derived quantities), and include such phenomena as velocity, force, and work. When we express length in meters and mass in kilograms we are using the units of the Systeme International d'Unites, referred to as the SI or the Meters, kilograms, and seconds (MKS) system. The concept of "work" in physics is decidedly more specific than its general meaning in daily life. In the physical sense, work (w) is done when the application of a force to a body results in its displacement. The problems involved with and related to such a wide range of values make it desirable to transform the absolute physical magnitudes into another form, called decibels (dB), which make the values both palatable and rationally meaning.