Theory
Protocols for centrifugation typically specify the amount of acceleration to be applied to the sample, rather than specifying a rotational speed such as revolutions per minute. This distinction is important because two rotors with different diameters running at the same rotational speed will subject samples to different accelerations. During circular motion the acceleration is the product of the radius and the square of the angular velocity, and the acceleration relative to "g" is traditionally named "relative centrifugal force" (RCF). The acceleration is measured in multiples of "g" (or × "g"), the standard acceleration due to gravity at the Earth's surface, a dimensionless quantity given by the expression:
where
- is earth's gravitational acceleration,
- is the rotational radius,
- is the angular velocity in radians per unit time
This relationship may be written as
where
- is the rotational radius measured in centimetres (cm), and
- is rotational speed measured in revolutions per minute (RPM).
Read more about this topic: Centrifuge
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