Until recently, lower-end and power-efficient laptop drives could be found with 4200 rpm or even 3600 rpm spindle speeds (70 Hz or 60 Hz), but these have fallen out of favour due to their lower performance, improvements in energy efficiency in faster models and the takeup of solid-state drives for use in slimline and ultraportable laptops. High-performance drives (used in fileservers and enthusiast-gaming PCs) rotate at 10 000 rpm – 15 000 rpm (160 Hz – 250 Hz), usually with higher-level SATA, SCSI or Fibre Channel interfaces and smaller platters to allow these higher speeds, the reduction in storage capacity and ultimate outer-edge speed paying off in much quicker access time and average transfer speed thanks to the high spin rate. Computer hard drives typically rotate at 5400 rpm – 7200 rpm (90 Hz – 120 Hz), the most common speeds for the ATA or SATA-based drives in consumer models. A piston aircraft engine typically rotates at a rate between 2000 rpm and 3000 rpm (30 Hz – 50 Hz).Thus an eight-cylinder engine turning 300 times per second will have an exhaust note of 1200 Hz. The exhaust note of V8, V10, and V12 F1 cars has a much higher pitch than an I4 engine, because each of the cylinders of a four-stroke engine fires once for every two revolutions of the crankshaft. Modern automobile engines are typically operated around 2000 rpm – 3000 rpm (33 Hz – 50 Hz) when cruising, with a minimum (idle) speed around 750 rpm – 900 rpm (12.5 Hz – 15 Hz), and an upper limit anywhere from 4500 rpm to 10 000 rpm (75 Hz – 166 Hz) for a road car, very rarely reaching up to 12 000 rpm for certain cars (such as the GMA T.50), or 20 000 rpm for racing engines such as those in Formula 1 cars (during the 2006 season, with the 2.4 L N/A V8 engine configuration limited to 15 000 rpm, with the 1.6 L V6 turbo- hybrid engine configuration).A power generation turbine ( with a two-pole alternator) rotates at 3000 rpm (50 Hz) or 3600 rpm (60 Hz), depending on country – see AC power plugs and sockets.A baseball thrown by a Major League Baseball pitcher can rotate at over 2500 rpm (41.7 Hz) faster rotation yields more movement on breaking balls.A washing machine's drum may rotate at 500 rpm to 2000 rpm (8 Hz – 33 Hz) during the spin cycles.The disc's rotational speed varies from 25.5 Hz (1530 rpm) when reading at the innermost edge, to 10.5 Hz (630 rpm) at the outer edge. DVD players also usually read discs at a constant linear rate.Audio CD players read their discs at a precise, constant rate (4.3218 Mbit/s of raw physical data for 1.4112 Mbit/s (176.4 KB/s) of usable audio data) and thus must vary the disc's rotational speed from 8 Hz (480 rpm) when reading at the innermost edge, to 3.5 Hz (210 rpm) at the outer edge.The second hand of a conventional analog clock rotates at 1 rpm.Modern air turbine dental drills can rotate at up to 800 000 rpm (13.3 kHz).Phonograph (gramophone) records, for example, typically rotate steadily at 16 + 2⁄ 3, 33 + 1⁄ 3, 45 rpm or 78 rpm (0.28, 0.55, 0.75, or 1.3, respectively, in Hz). On many kinds of disc recording media, the rotational speed of the medium under the read head is a standard given in rpm.A revolution is one complete period of motion, whether this be circular, reciprocating or some other periodic motion. For a wheel, a pump, or a crank shaft, the number of times that it completes one full cycle in one minute is given the unit revolution per minute.The conversions between a frequency f and an angular velocity ω are:įailed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server " Ī corresponding but distinct quantity for describing rotation is angular velocity, for which the SI unit is the radian per second.Īlthough they have the same dimensions (s −1), hertz (Hz) and radian per second (rad/s) are two different units and are used to measure two different but proportional ISQ quantities: frequency and angular frequency (angular speed, magnitude of angular velocity) respectively. It defines a unit of rotational frequency equal to s −1 ( reciprocal second). ISO 80000-3:2019 defines a unit of rotation as the dimensionless unit equal to 1, which it refers to as a revolution, but does not define the revolution as a unit. Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or r⋅min −1) is a unit of rotational speed or rotational frequency for rotating machines. JSTOR ( July 2016) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed.įind sources: "Revolutions per minute" – news Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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