Fig. 9. Relative contribution of forces in the direction of motion as a result of
buccal pressure (Fpressure), acceleration of mass and
added mass (Finertia) and hydrodynamic drag
(Fdrag) to the total force, as estimated by dynamic
modelling. Note that forces due to friction between head parts and from
deformation of tissues are not included in the model. No significant changes
with size are found.