Frequency rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light. For cyclical processes, such as rotation, oscillations, or waves, frequency is defined as a number of cycles per unit time. In physics and engineering disciplines, such as optics, acoustics, and radio, frequency is usually denoted by a Latin letter "f" or by the Greek letter "formula_1" or "ν" (nu) (see e.g. Planck's formula). The relation between the frequency and the period formula_2of a repeating event or oscillation is given by The SI derived unit of frequency is the hertz (Hz), named after the
Kilogram-force per square centimetre SI units, the unit is converted to the SI derived unit pascal (Pa), which is defined as one newton per square metre (N/m). A newton is equal to a kg·m/s, and a kilogram-force is 9.80665 newtons, meaning that 1 kgf/cm equals 98.0665 kilopascals (kPa). In some older publications, kilogram-force per square centimetre is abbreviated ksc instead of kg/cm. All the Russian origin gauges are indicating pressure in Kgf/cm2 and are calibrated annually. Kilogram-force per square centimetre A kilogram-force per centimetre square (kgf/cm), often just kilogram per square centimetre (kg/cm), or kilopond per centimetre square is a deprecated unit of pressure