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Volkswagen Golf Mk7 Owners Manual: Frontal collisions and the laws of physics

Fig. 59 and Fig. 60 illustrate unbelted occupants of a Volkswagen Golf Mk7 as it heads for, then strikes, a brick wall. This page explains the underlying physics in plain terms: once the car is moving, both the vehicle and everyone inside it carry that momentum, and only the seat belt — not the car's structure alone — brings an occupant's body to a stop safely.

Fig. 59 Unbelted occupants in a vehicle heading for a brick wall

Fig. 60 Unbelted occupants in a vehicle striking a brick wall

First read and observe the introductory information and safety warnings 

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 passengers gain kinetic energy.

The higher the vehicle speed and the heavier the weight of the vehicle, the greater the amount of energy that will have to be released in the event of an accident.

However, the most significant factor is the speed of the vehicle. If the speed doubles from approximately 25 km/h (15 mph) to approximately 50 km/h (30 mph), for example, 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  .

Even at speeds of approximately 30 km/h (18 mph) to approximately 50 km/h (30 mph), the forces acting on bodies in a collision can easily exceed one tonne (1,000 kg). These forces are even greater at higher speeds.

This example applies not only to frontal collisions, but to all accidents and collisions.

    Questions & answers

    Frontal collisions and the laws of physics — Volkswagen Golf Mk7

    What physics does the Golf Mk7 manual explain about frontal collisions?
    It explains that both the car and its occupants carry kinetic energy when moving. In a crash the car stops abruptly but unbelted occupants continue forward at the original speed, striking the interior with extreme force.
    How fast does crash force build up in the Golf Mk7?
    Even at 30 km/h the forces on the body are so large that no person can brace against them with their hands. At higher speeds the energy — and potential injuries — increase exponentially.
    Why does the Golf Mk7 manual include a physics section?
    It helps owners understand why seat belts and airbags are essential. Knowing that crash forces exceed human strength by many times reinforces the habit of always wearing a belt.
    Warning lamp
    Fig. 57 Warning lamp in the instrument cluster Fig. 58 Seat belt status for the rear seats in the instrument cluster First read and observe the introductory information and safety warnings� ...

    What happens to vehicle occupants who have not fastened their seat belts
    Fig. 61 An unbelted driver is thrown forwards Fig. 62 The unbelted rear passenger is thrown forwards, hitting the belted driver First read and observe the introductory information and safety ...

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