Centrifugation: to find the RCF given by a particular rotor at a particular RPM:
Centrifugation is an important step in pretty much every protein chemical and molecular biological procedure. The force exerted on a particle in a centrifuge is a simple function of the rotation speed of the centrifuge and the radius of rotation. The actual equation is RCF = 1.12R(RPM/1000)2, where RCF = relative centrifugal force, R is the radius of rotation measured in millimeters and RPM is the number of rotations per minute. RCF is the same as G force essentially; an RCF of 100 would be equivalent to a gravitational field of 100G. The R in this equation must be measured in millimeters, if you measure in inches the formula won't work. The R value can be measured at the top of the tube (RMin), the middle of the tube (RAv) or the bottom of the tube (RMax). Since protocols often don't specify which value is meant, you may have to take your best guess as to which one to use. If you are trying to pellet something out, you should probably use RMax, since obviously the pellet forms at the bottom of the tube. This particular program will calculate the RCF if you enter the R value in millimeters and the RPM. To calculate the RPM you need to get a particular RCF from a particular sized rotor go here