Rotor radius
= Rotor radius
{title2=$r$}
The <rotor radius> $r$ is the perpendicular distance from the rotation axis to a specified sample position, not the tube's length. A filled tube spans a range $r_{\min}\leq r\leq r_{\max}$. Consequently, one rotational speed produces different local <centrifugal accelerations> along that range. A reported <relative centrifugal force> needs a stated reference position, such as the outermost sample radius.