# Revolutions per minute

rpmr.p.m.RPMsrevolutions78 RPMrevsrotational speedrotations per minuteengine speedengine speeds
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min −1 ) is the number of turns in one minute.wikipedia
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### Rotational speed

rotational velocityrotation speedrotational speeds
It is a unit of rotational speed or the frequency of rotation around a fixed axis.
Rotational speed (or speed of revolution) of an object rotating around an axis is the number of turns of the object divided by time, specified as revolutions per minute (rpm), cycles per second (cps), radians per second (rad/s), etc..

### Rotation around a fixed axis

axis of rotationaxisaxial
It is a unit of rotational speed or the frequency of rotation around a fixed axis.
In mathematics and physics it is usual to use the natural unit radians rather than degrees or revolutions.

### Frequency

frequenciesperiodperiodic
It is a unit of rotational speed or the frequency of rotation around a fixed axis.
A traditional unit of measure used with rotating mechanical devices is revolutions per minute, abbreviated r/min or rpm.

### Phonograph record

vinyl7LP
Phonograph records are generally described by their diameter in inches (12-inch, 10-inch, 7-inch), the rotational speed in revolutions per minute (rpm) at which they are played (8 1⁄3, 16 2⁄3, 33 1⁄3, 45, 78), and their time capacity, determined by their diameter and speed (LP [long playing], 12-inch disc, 33 1⁄3 rpm; SP [single], 10-inch disc, 78 rpm, or 7-inch disc, 45 rpm; EP [extended play], 12-inch disc or 7-inch disc, 33 1⁄3 or 45 rpm); their reproductive quality, or level of fidelity (high-fidelity, orthophonic, full-range, etc.); and the number of audio channels (mono, stereo, quad, etc.).

### Turn (angle)

turnturnsrevolution
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min −1 ) is the number of turns in one minute.

When measuring angular speed, the unit radians per second is used.
For example, if one multiplies angular velocity in revolutions per minute (rpm) by the torque in pound-feet, then a factor is needed to convert the result in horsepower.

### Dental drill

dental handpiecedentist's drillburr
Like most hand drills, they were quite slow, with speeds of up to 15 rpm.

### Hard disk drive

hard drivehard diskhard drives
Performance is specified by the time required to move the heads to a track or cylinder (average access time) adding the time it takes for the desired sector to move under the head (average latency, which is a function of the physical rotational speed in revolutions per minute), and finally the speed at which the data is transmitted (data rate).

### Washing machine

washing machineswasherclothes washer

### Alternator

turbo-alternatoralternatorsgenerator
P is the number of poles (2, 4, 6, …) and N is the rotational speed in revolutions per minute (RPM).

### Four-stroke engine

four-stroke4-strokefour stroke
The amount of power generated by a piston engine is related to its size (cylinder volume), whether it is a two-stroke engine or four-stroke design, volumetric efficiency, losses, air-to-fuel ratio, the calorific value of the fuel, oxygen content of the air and speed (RPM).

### Formula One engines

Power unitengineMGU-K

### Zippe-type centrifuge

gas-centrifugecentrifugenuclear centrifuge
Separation of uranium isotopes requires a centrifuge that can spin at 1,500 revolutions per second (90,000 RPM).

### Formula One car

Formula One racing carcarsFormula One cars

### Overspeed

overspeedingOverspeed (engine)overspeeds
The speed of an engine is ordinarily measured in revolutions per minute (RPM).

### Engine

enginesmotormotors
Given that the majority of engines for which a speed is defined rotate, engine speed is measured in revolutions per minute (RPM).

### Flagellum

flagellaflagellatedflagellar
The rotor alone can operate at 6,000 to 17,000 rpm, but with the flagellar filament attached usually only reaches 200 to 1000 rpm.

### Rev limiter

rev limitlimiterrev limited
They are intended to protect an engine by restricting its maximum rotational speed, measured in revolutions per minute (RPM).

### Solid-state drive

SSDsolid state drivesolid-state drives

### Constant linear velocity

CLVzoned constant linear velocitylinear velocity
CLV implies that the angular velocity (i.e. rpm) varies during an operation, as contrasted with CAV modes.

### Redline

redliningengine revolutionsrev limit
Redlines vary anywhere from a few hundred revolutions per minute (rpm) (in very large engines such as those in trains and generators) to more than 10,000 rpm (in smaller, usually high-performance engines such as motorcycles and sports cars with pistonless rotary engines).

### Idle speed

idleidlingidle power
In combustion engines, idle speed is generally measured in revolutions per minute (rpm) of the crankshaft.

### Minute

minmmins.
Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min −1 ) is the number of turns in one minute.

### International System of Units

SISI unitsSI unit
According to the International System of Units (SI), rpm is not a unit.

### Semantics

semanticsemanticallymeaning
This is because the word revolution is a semantic annotation rather than a unit.