Revolutions per minute
:
rpm redirects here. For other uses, see
rpm (disambiguation)For the Rise Against album, see Revolutions Per Minute (album).For the Jason Trachtenburg album, see Revolutions Per Minute (Jason Trachtenburg album).Revolutions per minute (abbreviated
rpm,
RPM,
r/min, or
min−1) is a
unit of
frequency, commonly used to measure
rotational speed, in particular in the case of
rotation around a fixed axis. It represents the number of full rotations something makes in one minute. The unit for rotational velocity is the
radian per second (
rad·s−1).
* The sweep second hand of a clock or watch rotates at 1 rpm.
*
Gramophone (phonograph) records typically rotate steadily at 16, 33â…", 45 or 78 rpm.
*
Audio CD rotation rates vary from about 500 rpm when reading the innermost data track, to 180 rpm when reading tracks near the outer edge.
* A
washing machine's drum may rotate at 500 to 1800 rpm during the spin cycles.
* An
automobile's
engine typically varies between 700 and 7000 rpm.
* A piston
aircraft engine typically rotates between 2000 and 3000 rpm.
* A computer's
hard drive rotates at 3600, 4200, 5400, or 7200 rpm on
IDE types and 10 000 or 15 000 rpm on some
SATA and
SCSI and
Fibre Channel drives.
* A
racing car engine's limits is close to 20 000 rpm in
Formula One.
* A 52×
CD-ROM drive can rotate a
CD as fast as 10 350 rpm.
* A
Zippe-type centrifuge for enriching uranium spins at 90 000 rpm or faster.
*
Gas turbine engines rotate at tens of thousands of rpm.
JetCat model aircraft turbines are capable of over 100 000 rpm with the fastest hitting 165 000 rpm.
s generally recommend the symbol
r/min, which better follows the general principles for forming unit symbols. But this is not enforced in fully metric countries as an international standard; for example, the French use the symbol
tr/mn ('tours par minute').
The unit of
frequency is the
hertz (Hz): :1 r/min = 1/60 Hz ::*This is often used for measuring waves, such as radio and sound.
The
SI unit of
angular speed is the
radian per second: :1 rev/min = 2Ï€ rad·min
−1 = 2Ï€/60 rad·s
−1 = 0.10471976 rad·s
−1 online converterHowever, there is no movement to use either of these units of measure (which are primarily used in
physics) to replace
revolutions per minute when measuring the rotational speed of machinery.
*
Radian per second*
Orders of magnitude (angular velocity)*
Constant linear velocity, or
CLV, used when referring to the speed of audio CD's
*
Constant angular velocity, or
CAV, used when referring the speed of gramophone (phonograph) records
*
Turn (geometry)*
UnitConverterPro.com online angular velocity conversion
