Frontal collisions and the laws of physics
Fig. 1 Unbelted occupants in a vehicle heading for a brick wall.
Fig. 2 Unbelted occupants in a vehicle heading for a brick wall.
The physical principles involved in a frontal collision are relatively simple. As soon as the vehicle
is in motion, both the moving vehicle and its occupants gain “kinetic energy” → Fig. 1 .
The higher the vehicle speed and the heavier the weight of the vehicle, the greater the amount
of energy that will be released in the event of an accident.
However, the most significant factor is the speed of the vehicle. For example, if the speed
doubles from around 25 km/h to around 50 km/h (15 mph to 31 mph), the kinetic energy
increases by a factor of four.
The amount of “kinetic energy” depends on the speed of the vehicle and the weight of the
vehicle and passengers. The higher the speed and the heavier the weight, the greater the amount
of energy that will be released in the event of an accident.
Passengers not wearing seat belts are not “connected” to the vehicle. In the event of a frontal
collision, they will continue to move forwards at the same speed at which the vehicle was
travelling before impact, until something stops them. Because the passengers in our example are
not restrained by seat belts, the entire amount of kinetic energy will only be released at the point
of impact against the wall → Fig. 2 .
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