Glossary
Revolutions per minute (RPM)
RPM is how fast a rotor turns. It is a property of the motor, not of the sample, and on its own it says nothing about the force reaching the blood. Converting RPM to force requires the radius of the specific rotor being used.
In practice
This is why a protocol reported only in RPM cannot be reproduced by a clinic with a different machine. A rotor with twice the radius delivers twice the force at identical RPM.
See also