Revolutions per minute

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:

RPM (disambiguation)

RPM is an abbreviation of revolutions per minute, a measure of rotation frequency.

RPM may also refer to:

Business

Computers

Film and TV

LP record

The LP (long play), or 33 ¹⁄₃ rpm microgroove vinyl record, is a format for phonograph (gramophone) records, an analog sound storage medium. Introduced by Columbia Records in 1948, it was soon adopted as a new standard by the entire record industry. Apart from relatively minor refinements and the important later addition of stereophonic sound capability, it has remained the standard format for vinyl albums.

Format advantages

At the time the LP was introduced, nearly all phonograph records for home use were made of an abrasive (and therefore noisy) shellac compound, employed a much larger groove, and played at approximately 78 revolutions per minute (rpm), limiting the playing time of a 12-inch diameter record to less than five minutes per side. The new product was a 12- or 10-inch (30 or 25 cm) fine-grooved disc made of vinyl and played with a smaller-tipped "microgroove" stylus at a speed of 33 ¹⁄₃ rpm. Each side of a 12-inch LP could play for more than 20 minutes. Only the microgroove standard was truly new, as both vinyl and the 33 ¹⁄₃ rpm speed had been used for special purposes for many years, as well as in one unsuccessful earlier attempt to introduce a long-playing record for home use.

45 RPM

45 RPM or 45 rpm may refer to:

Vinyl record format

Music

Artists

Album titles

Song titles

33 ⅓ RPM

33 ⅓ RPM refers to:

Gramophone record

A gramophone record (phonograph record in American English) or vinyl record, commonly known as a "record", is an analog sound storage medium in the form of a flat polyvinyl chloride (previously shellac) disc with an inscribed, modulated spiral groove. The groove usually starts near the periphery and ends near the center of the disc. Phonograph records are generally described by their diameter in inches (12", 10", 7"), the rotational speed in rpm at which they are played (16 ²⁄₃, 33 ¹⁄₃, 45, 78), and their time capacity resulting from a combination of those parameters (LP – long playing 33 ¹⁄₃ rpm, SP – 78 rpm single, EP – 12-inch single or extended play, 33 or 45 rpm); their reproductive quality or level of fidelity (high-fidelity, orthophonic, full-range, etc.), and the number of audio channels provided (mono, stereo, quad, etc.).

The phonograph disc record was the primary medium used for music reproduction until late in the 20th century, replacing the phonograph cylinder record, with which it had co-existed, by the 1920s. By the late 1980s, digital media, in the form of the compact disc, had gained a larger market share, and the vinyl record left the mainstream in 1991. After its fall, records continued to be manufactured and sold, and have been especially used by disc jockeys and many audiophiles for various types of music. The phonograph record has made a niche resurgence in the early 21st century – 9.2 million records were sold in the U.S. in 2014, a 260% increase since 2009. Likewise, in the UK sales have increased five-fold from 2009 to 2014.