ON BINARY IMPACTS OF SMALL LIQUID-FILLED SHELLS

We report the peculiar impact properties of small spherical shells fil led with a viscous liquid. Upon collisions of two identical Liquid-fil led shells, the fluid is progressively set in relation by the shell sp in induced by tangential impact forces. An analysis of the correspondi ng fluid motion predicts a collision outcome unlike that of solid sphe res where angular velocity is uniform, Observations of colliding vitam in-E pills reveal that the point of contact is rarely involved In gros s slip. In the direction of the line of centers, collisions are adequa tely described by a kinematic restitution coefficient. In the perpendi cular direction, they generally exhibit rolling contact. (C) 1997 Amer ican Institute of Physics. [S1070-6631(97)00512-6].