We proposed a model based on the falling of rigid bar, which was improved both hypothesis of the rotational & free falling and a rigid pendulum. Our models showed that the normal force of rigid bar became zero value by the way of the falling process. When the ratio (friction/normal force) went beyond a coefficient of static friction μ_0 and an angular θ satisfied with a relation θ_1 < θ <cos^<-1> (1/3), the friction force acted to opposite direction so as to counteract a centrifugal force of the falling rigid bar. This inversed frictions being caused by the centrifugal force corresponded to a stress, that stress prevented the dummy from being outthrown.
