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From Wikipedia, the free encyclopedia

Revolutions per minute (abbreviated rpm, RPM, r/min, or r·min−1) is a unit of frequency of rotation: the number of full rotations completed in one minute around a fixed axis. It is used as a measure of rotational speed of a mechanical component.

Standards organizations generally recommend the symbol r/min, which is more consistent with the general use of unit symbols. This is not enforced as an international standard. In French for example, tr/mn (tours par minute) is commonly used, and the German unit reads U/min (Umdrehungen pro Minute) or 1/min (= 1 min-1).

The corresponding unit in the International System of Units (SI) is hertz (symbol Hz) or s-1 (1/second). Revolutions per minute is converted to hertz through division by 60. Conversion from hertz to rpm is by multiplication by 60.

1 rpm = 1/min = 1/(60s) = 1/60 Hertz ≈ 0.01667 Hz

Another related unit is the SI unit for angular velocity, radian per second (rad·s−1):

1 rpm = 2π rad·min−1 = 2π/60 rad·s−1 ≈ 0.10471976 rad·s−1

Examples

  • On some kinds of disc or tape-like recording media, the rotational speed of the medium under the read head is a standard given in r/min. Gramophone (phonograph) records, for example, typically rotate steadily at 16+23, 33+13, 45 or 78 r/min (518, 59, 34, or 1.3 Hz respectively).
  • Modern ultrasonic dental drills can rotate at up to 800,000 r/min (13.3 kHz).
  • The "second" hand of a conventional analogue clock rotates at 1 r/min.
  • Audio CD players read their discs at a constant 150 kB/s and thus must vary the disc's rotational speed from around 500 r/min (actually 8 Hz), when reading at the innermost edge, to 200 r/min (actually 3.5 Hz) at the outer edge.[1] CD-ROM drives’ maximum rotational speeds are rated in multiples of this figure, even though they do not hold to constant read speeds when reading from most disc formats.
  • DVD players also usually read discs at a constant linear rate. The disc's rotational speed varies from 1530 r/min (actually 25.5 Hz), when reading at the innermost edge, and 630 r/min (actually 10.5 Hz) at the outer edge.[1] DVD drives’ speeds are usually given in multiples of this figure.
  • A washing machine's drum may rotate at 500 to 2000 r/min (8–33 Hz) during the spin cycles.
  • A power generation turbine rotates at 3000 r/min (50 hz) or 3600 r/min (60 Hz), depending on country - see AC power plugs and sockets.
  • Automobile engines are usually operated at 2500 r/min (41 Hz), with the minimum speed usually around 1000 r/min (16 Hz), and the redline at 6000-10,000 r/min (100-166 Hz).
  • A piston aircraft engine typically rotates at a rate between 2000 and 3000 r/min (30–50 Hz).
  • Computers’ hard drives typically rotate at 5400 or 7200 r/min (90 or 120 Hz)—most commonly with ATA or SATA interfaces—and some high-performance drives rotate at 10,000 or 15,000 r/min (160 or 250 Hz)—usually with SATA, SCSI or Fibre Channel interfaces.
  • The engine of a Formula One racing car can reach 19,000 r/min (320 Hz) under some circumstances.[2]
  • A Zippe-type centrifuge for enriching uranium spins at 90,000 r/min (1,500 Hz) or faster.[3]
  • Gas turbine engines rotate at tens of thousands of r/min. JetCat model aircraft turbines are capable of over 100,000 r/min (1,700 Hz) with the fastest reaching 165,000 r/min (2,750 Hz).[4]
  • An electromechanical battery (EMB) works at 60,000–200,000 r/min (1–3 kHz) range using a passively magnetic levitated flywheel in vacuum.[5] The choice of the flywheel material is not the most dense, but the one that pulverises the most safely, at surface speeds about 7 times the speed of sound.
  • A turbocharger can reach 290,000 r/min (4,800 Hz), while 80,000–200,000 r/min (1–3 kHz) is common.
  • a bullet fired from an M16A2 rifle, using a 5.56x45mm NATO rifle cartridge, spins at ~315,000 r/min.

See also

References

  1. ^ a b "Physical parameters of DVD". DVD Technical Notes. Moving Picture Experts Group (MPEG). 1996-07-21. http://www.mpeg.org/MPEG/DVD/Book_A/Specs.html. Retrieved 2008-05-30. 
  2. ^ "The Official Formula 1 Website". formula1.com. http://www.formula1.com/inside_f1/understanding_the_sport/5280.html. Retrieved 2008-05-13. 
  3. ^ "Slender and Elegant, It Fuels the Bomb". electricityforum.com. http://www.electricityforum.com/news/mar04/centrifuge.html. Retrieved 2006-09-24. 
  4. ^ "JetCat P-60 turbine specification page". jetcat.com. http://www.jetcatusa.com/p60.html. Retrieved 2006-07-19. 
  5. ^
    • A typical 80mm, 30 CFM computer fan will spin at 2,600-3,000 r/min on 12 V DC power.
    Post, Richard F. (1996), "A New Look at an Old Idea: The Electromechanical Battery", Science & Technology Review (Livermore, CA: University of California, Lawrence Livermore National Laboratory): 12–19, April 1996, ISSN: 10923055, http://www.llnl.gov/str/pdfs/04_96.2.pdf, retrieved 2008-05-30 
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Simple English

Revolutions per Minute
Studio album by Rise Against
Released April 8, 2003
Recorded Nov–Dec 2002 at the Blasting Room, Fort Collins, Colorado, USA
Genre Post-hardcore, punk rock
Length 37:42
Label Fat Wreck Chords
Producer Bill Stevenson
Jason Livermore
Professional reviews
Rise Against chronology
The Unraveling
(2001)
Revolutions per Minute
(2003)
Siren Song of the Counter Culture
(2004)

Revolutions per Minute is the second album by the American punk rock band Rise Against. It has the singles "Heaven Knows" and "Like the Angel" as well as a cover of Journey's single, "Any Way You Want It."

The album had a limited release on vinyl (217 of which were on red vinyl) which is now out of print.[needs proof] It was the band's last release under Fat Wreck Chords before to their move to Geffen Records. This is where they released Siren Song of the Counter Culture in 2004. It is interesting to note that inside the album cover, there is a copyright to Transistor Revolt, the band's name before they changed it to Rise Against.

Track listing

  1. "Black Masks and Gasoline" – 2:59
  2. "Heaven Knows" – 3:23
  3. "Dead Ringer" – 1:31
  4. "Halfway There" – 3:41
  5. "Like the Angel" – 2:46
  6. "Voices off Camera" – 2:17
  7. "Blood-Red, White, and Blue" – 3:38
  8. "Broken English" – 3:25
  9. "Last Chance Blueprint" – 2:14
  10. "To the Core" – 1:33
  11. "Torches" – 3:41
  12. "Amber Changing" – 3:39
  13. "Any Way You Want It" (Journey cover) – 2:57
  • Track 13 is a hidden track

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