(abbreviated '''rpm''', '''RPM''', '''r/min''', or '''r·min−1''') is a . It is most commonly used as a measure of Rotational Speed or Angular Velocity of some mechanical component.
Standards Organization s generally recommend the symbol '', 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.
The corresponding International System Of Units (SI) unit would be the and we have:
:1 r/min = (1/60) revolutions per Second = 0.01666667 Hz
In the SI one often uses the unit for angular velocity which is ('''rad·s−1'''):
:1 r/min = 2π rad·min−1 = 2π/60 rad·s−1 = 0.10471976 rad·s−1
See Also: Orders of magnitude (angular velocity)
- 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, 33⅓, 45 or 78 r/min.
- Modern Dental Drill s can rotate at up to 500,000 r/min.
- The second hand of a conventional analogue clock rotates at 1 r/min.
- Audio CD players read their discs at a constant 150KB/s and thus must vary the disc's rotational speed from around 500 r/min when reading at the innermost edge, and 180 r/min at the outer edge. CD-ROM drives have their maximum rotational speeds are rated in multiples of this figure, even though they do not hold to constant read speeds when reading from data tracks.
- A Washing Machine 's drum may rotate at 500 to 1800 r/min during the spin cycles.
- An Automobile 's Engine typically varies between 700 and 7000 r/min (though there are certain cars that can rev as high as 11,000 r/min.
- A piston Aircraft Engine typically rotates between 2000 and 3000 r/min.
- A computer's Hard Drive rotates at 3600, 4200, 5400, or 7200 r/min on IDE types and 10 000 or 15 000 r/min on some SATA and SCSI and Fibre Channel drives.
- The engine of a Formula One racing car can reach 20,000 r/min under some circumstances.1
- A Zippe-type Centrifuge for enriching uranium spins at 90 000 r/min or faster.2
- Gas Turbine engines rotate at tens of thousands of r/min. JetCat model aircraft turbines are capable of over 100 000 r/min with the fastest hitting 165 000 r/min.3
- An Electromechanical Battery (EMB) works at 60 000 - 200 000 rpm range using a passively magnetic levitated flywheel in vacuum4. 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 while 80 000 - 200 000 r/min are common.
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