Rotational speed
The speed or frequency of revolution is a size that at - tells how many complete rotations - preferably mechanical. It is, for example, an essential characteristic for the labeling of the performance parameters for engines. The information is given in the art mostly in revolutions per minute (min -1), in physics rather in revolutions per second (s- 1).
The speed is the reciprocal value of the orbital period.
The size of " speed" in turns corresponds to the size " frequency " in other periodic processes, such as vibrations.
The speed measurement can be done in different ways, such as by measuring the orbital period, by comparison with a known stroboscopic frequency, by measuring an induced voltage, etc.
Definition and unit
Set the speed by the number of rotations within a selectable time interval is notably based on this time interval
The unit of speed according to the SI system of units. Frequently used and common in engineering and related fields, the information is in (per minute). The special name revolution ( unit symbol r, in German-speaking U) is widely used as a unit in the specification for rotating machines used instead of one. Accordingly, the rotation units are widely used by second ( unit symbol in the German-speaking U / s) or turn by minute ( unit symbol U / min) at the speed. According to DIN 1301, this notation should be avoided with use of an auxiliary unit. The notation in the text is here min - 1 (Example: 5700 min -1) or 1/min ( the count of the speed must be at the counter, for example, 5700 rpm ).
The unit Hertz, must be used only in the frequency, but not in the rotational speed. In English usage is rpm or r / encountered min ( revolutions per minute ) or rps ( revolutions per second).
The angular speed is also in the unit 1 / s or rad / s, the unit rad (radian ) at an angle points. This is in accordance with
Since a full rotation corresponds to an angle 2π, is the angular velocity to the speed in relationship over