Investigates the kinematics in centrifuge modelling which are highly useful for improving the understanding of results from centrifuge modelling tests. Mathematical expressions of the global velocity and acceleration of an arbitrary particle in a centrifuge model

which describe the motion of the particle

are derived. The acceleration is a critical factor in centrifuge modelling because it links kinematics to dynamics through Newton second law. The physical meaning of each term of the derived expression for global acceleration is described. Contributions of the centripetal acceleration in steady flight

the tangential acceleration due to the effect of the angular acceleration

the Coriolis component of acceleration

the radial (the vertical direction at prototype)

circumferential and axial (the two horizontal directions at prototype) shaking effects and the elongation effect of the centrifuge arm to the global acceleration of a particle in centrifuge modelling are identified in the expression of the global acceleration. It is found that

for ease of comprehension of test results from dynamic centrifuge modelling by means of uniaxial shaking

the preferred direction of shaking is in the axial direction (parallel to the axis of rotation). In addition

a description of the kinematics in centrifuge modelling proposed by Schofield [1] is critically examined and is found to be confusing.