Vehicle Safety is very attractive, concerning active or passive safety. The collisions are intensively studied including deformations, kinematics, protections, devices and injuries. By the way, today we have a lot of computer programs trying to simulate these crash-tests. But, we can have an idea about the magnitude of the impact forces of a vehicle against a rigid wall starting from known physical concepts and simplified approximations. This is one of the purposes of this work.
The classic problem of projectile impacts against a rigid wall and the example of an aircraft impact against a nuclear power plant are used to consider the models applied to vehicles.
We consider the disacceleration of a material point and also the vehicle as an extense object.
Real data are used to quantify the achieved expressions. We compare and discuss the magnitude of the forces, for instance, between a passenger car and a commercial vehicle. We use the results to discuss the qualification of seat anchorage, some parameters concerning deformation and aspects of frontal impacts regarding passenger cars and commercial vehicles.