The exchange of energy between bodies involved in an impact depends upon the elastic properties of the bodies and, owing to the sequence of the dynamic reaction during the impact, upon the shape of the impact bodies. In the case of ball and plate, the conditions in this respect are extreme ones. With regard to the forces of reaction caused by the impact of a passenger against the fastened windshield, the different reactions of the various types of safety glass have to be taken into account. In particular, the forces of reaction and the reaction times occurring must remain within human tolerance limits. New windshield systems are presented which take into account the human tolerance values of the cervical spine.