Revolutions per minute

"RPM" and "rpm" redirect here. For other uses, see RPM (disambiguation).

Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min) is a measure of the frequency of rotation, specifically the number of rotations around a fixed axis in one minute. It is used as a measure of rotational speed of a mechanical component. In the French language, tr/mn (tours par minute) is the common abbreviation. The German language uses the abbreviation U/min or u/min (Umdrehungen pro Minute).

International System of Units

According to the International System of Units (SI), rpm is not a unit. This is because the word revolution is a semantic annotation rather than a unit. The annotation is instead done as a subscript of the formula sign if needed. Because of the measured physical quantity, the formula sign has to be f for (rotational) frequency and ω or Ω for angular velocity. The corresponding basic SI derived unit is s−1 or Hz. When measuring angular speed, the unit radians per second is used.

Here the sign ↔ (correspondent) is used instead of = (equal). Formally, hertz (Hz) and radian per second (rad/s) are two different names for the same SI unit, s−1. However, they are used for two different but proportional ISQ quantities: frequency and angular frequency (angular speed, magnitude of angular velocity). The conversion between a frequency f (measured in hertz) and an angular velocity ω (measured in radians per second) are:

Thus a disc rotating at 60 rpm is said to be rotating at either 2π rad/s or 1 Hz, where the 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 2π radians, then .

Examples

See also

References

  1. 1 2 "Physical parameters". DVD Technical Notes. Moving Picture Experts Group (MPEG). 1996-07-21. Retrieved 2008-05-30.
  2. "2014 season changes". Formula One. Retrieved 2014-08-18.
  3. "Double-Density Versus High-Density Disks". Apple. Retrieved 2012-05-05.
  4. "Slender and Elegant, It Fuels the Bomb". The Electricity Forum. Retrieved 2006-09-24.
  5. "P60-SE Special Edition". JetCat USA. Retrieved 2006-07-19.
  6. Post, Richard F. (April 1996). "A New Look at an Old Idea: The Electromechanical Battery" (PDF). Science & Technology Review. University of California: 12–19. ISSN 1092-3055. Retrieved 2008-05-30.
  7. Magariyama, Y.; Sugiyama, S.; Muramoto, K.; Maekawa, Y.; Kawagishi, I.; Imae, Y.; Kudo, S. (October 27, 1994). "Very fast flagellar rotation". Nature. 371 (6500): 752. Bibcode:1994Natur.371..752M. doi:10.1038/371752b0.
This article is issued from Wikipedia - version of the 9/12/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.