Abstract
The impact motion of a spherical body or a body with rectangular-grooved-surface towards a plane was analysed considering the structural force of the intervening liquid. The groove depth, d_g, and the groove ratio, r_g, were introduced as parameters for the rectangular-grooved-surface. The effects of d_g and r_g on the structural force and the dynamic motion were investigated and it was clarified that the effects can be explained in terms of the potential energy by the structural force.