Radian per second frequency, , corresponds to an ordinary frequency, , which corresponds to a frequency of rotation of . Radian per second The radian per second (symbol: rad·s or rad/s) is the SI unit of rotational speed (angular velocity), commonly denoted by the Greek letter "ω" (omega). The radian per second is also the unit of angular frequency. The radian per second is defined as the change in the orientation of an object, in radians, every second. Since the radian is a dimensionless unit, the radian per second is dimensionally equivalent to the hertz—both are defined as s. This may lead to
Revolutions per minute former measures the angular velocity and the latter reflects the number of revolutions per second. If the non-SI unit rpm is considered a unit of frequency, then . If it instead is considered a unit of angular velocity and the word "revolution" is considered to mean 2 radians, then . Revolutions per minute Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min) is the number of turns in one minute. It is a unit of rotational speed or the frequency of rotation around a fixed axis. According to the International System of Units (SI), rpm is