Audi A4 Owner's Manual page 198

document_0900452a81b1b9de.book Seite 196 Donnerstag, 26. Juli 2007 9:16 09
196 Seat belts
The physical principles involved in a frontal collision are relatively
simple:
Both the moving vehicle and the passengers possess energy, which
is known as "kinetic energy" ⇒ page 195, fig. 204. 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 greater
the weight, the more energy there is to be absorbed in an accident.
The most significant factor, however, is the speed of the vehicle. If
the speed doubles from 25 km/h to 50 km/h, for example, the kinetic
energy increases by a factor of four. Because these passengers are
not restrained by seat belts, the entire amount of kinetic energy has
to be absorbed at the point of impact ⇒ fig. 205. This would result
in serious or potentially fatal injury.
Even at urban speeds of 30 km/h to 50 km/h, the forces acting on the
occupants in a collision can reach the equivalent of 1 ton (1000 kg)
or more. At greater speed these forces are even higher. A rule of
thumb: if the speed doubles, the forces increase by a factor of four.
Passengers who do not wear seat belts are not "attached" to the
vehicle. In a frontal collision they will continue to move forward at
the speed their car was travelling just before the impact.
What happens to passengers not wearing
seat belts?
Passengers not wearing seat belts risk fatal injuries in the
event of an accident.
Fig. 205 The vehicle
crashes against the
wall
In a frontal collision, unbelted passengers will be thrown forwards
and make violent contact with the steering wheel, dashboard, wind-
screen, etc ⇒ fig. 206. Passengers not wearing their belts risk being
thrown out of the car, resulting in potentially fatal injuries.
The common belief that occupants can brace their weight with their
hands in a minor collision is false. Even at low speeds the forces
acting on the body in a collision are so great that it is not possible
to hold yourself in the seat.
Fig. 206 A driver not
wearing a seat belt can
be thrown forwards
Fig. 207 A rear
passenger not wearing
a seat belt can be
thrown forwards