What is a RPM (Revolutions Per Minute)?

Revolutions per minute (RPM or revs/min) is a measure of motor’s rotational frequency. Let’s say a motor’s fan speed is 5 RPM, its shaft would be making 5 complete rotations in a minute, around its axis of rotation. The more the number of RPMs of a motor, the more would be the speed of the motor.

Definition

“Revolutions per minute(abbreviated rpm, RPM, r/min, or r·min−1) is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis. It is used as a measure of rotational speed of a 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”

Some Examples

  1. On many kinds of disc recording media, the rotational speed of the medium under the read head is a standard given in rpm.Gramophone (phonograph) records, for example, typically rotate steadily at162⁄3,331⁄3, 45 or 78 rpm (5⁄18,5⁄9,3⁄4, or 1.3Hz respectively).
  2. Modern ultrasonic dental drills can rotate at up to 800,000 rpm (13.3kHz).
  3. washing machine‘s drum may rotate at 500 to 2000 rpm (8–33Hz) during the spin cycles.”

Source: http://en.wikipedia.org/wiki/Revolutions_per_minute