Hertz radians per second. Thus a disc rotating at 60 revolutions per minute (rpm) is said to be rotating at either 2 rad/s "or" 1 Hz, where the former measures the angular velocity and the latter reflects the number of "complete" revolutions per second. The conversion between a frequency "f" measured in hertz and an angular velocity "ω" measured in radians per second is The hertz is named after the German physicist Heinrich Hertz (1857–1894), who made important scientific contributions to the study of electromagnetism. The name was established by the International Electrotechnical Commission (IEC) in 1930. It was adopted by
Angular frequency for the vector quantity angular velocity. One revolution is equal to 2π radians, hence where ω is referred to as the natural frequency (which can sometimes be denoted as ω). As the object oscillates, its acceleration can be calculated by where "x" is displacement from an equilibrium position. Using "ordinary" revolutions-per-second frequency, this equation would be The resonant angular frequency in a series LC circuit equals the square root of the reciprocal of the product of the capacitance ("C" measured in farads) and the inductance of the circuit ("L", with SI unit henry): Adding series resistance (for example, due to