Revolutions Per Minute

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Revolutions per minute (abbreviated rpm, RPM, r/min, or r·min−1) is a units of measurement of frequency: the number of full rotations completed in one minute around a rotation around a fixed axis. It is most commonly used as a measure of rotational speed or angular velocity of some 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.

The corresponding SI unit would be the hertz 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 radian per second (rad·s−1): 1 r/min = 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 record, for example, typically rotate steadily at 16, 33⅓, 45 or 78 r/min.
Modern dental drills 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 Advanced Technology Attachment types and 10 000 or 15 000 r/min on some Serial ATA and SCSI and Fibre Channel drives.
The engine of a Formula One racing car can reach 20,000 r/min under some circumstances.
A Zippe-type centrifuge for enriching uranium spins at 90 000 r/min or faster.
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 reaching 165 000 r/min.

An electromechanical battery (EMB) works at 60 000 - 200 000 rpm range using a passively magnetic levitated flywheel in vacuum. 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.

See also

Orders of magnitude (angular velocity)
Constant linear velocity, or CLV, used when referring to the speed of audio CDs
Constant angular velocity, or CAV, used when referring the speed of gramophone (phonograph) records
Turn (geometry)

References

Revolutions per minute (abbreviated rpm, RPM, r/min, or r·min−1) is a units of measurement of frequency: the number of full rotations completed in one minute around a rotation around a fixed axis. It is most commonly used as a measure of rotational speed or angular velocity of some 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.

The corresponding SI unit would be the hertz 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 radian per second (rad·s−1): 1 r/min = 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 record, for example, typically rotate steadily at 16, 33⅓, 45 or 78 r/min.
Modern dental drills 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 Advanced Technology Attachment types and 10 000 or 15 000 r/min on some Serial ATA and SCSI and Fibre Channel drives.
The engine of a Formula One racing car can reach 20,000 r/min under some circumstances.
A Zippe-type centrifuge for enriching uranium spins at 90 000 r/min or faster.
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 reaching 165 000 r/min.

An electromechanical battery (EMB) works at 60 000 - 200 000 rpm range using a passively magnetic levitated flywheel in vacuum. 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.