A green light indicates that the seat’s oc-
cupant is wearing the seat belt.
A red light indicates that the seat is occu-
pied and the occupant is not wearing the
seat belt.
If a speed of 25km/h (15mph) is exceeded
after moving o without the driver or a front
passenger seatbelt being fastened, or if the
seatbelt is unfastened while driving, an audible
signal will sound for 126 seconds. In addition,
the warning lamp on the instrument cluster
display ashes.
The lamp goes out when the ignition is
on and all occupants have fastened their seat
belts.
Head-on collisions and the laws of
physics
Fig.21 A driver not wearing a seat belt
may be thrown forward violently.
Fig.22 Any rear seat occupants not
wearing a seat belt may be thrown forward
violently, hitting the driver who is wearing
the seat belt.
The eects of the laws of physics in the case
of a head-on collision are easy to explain: the
moment a vehicle starts moving, a type of en-
ergy called “kinetic energy” starts acting on
both the vehicle and its passengers.
The amount of “kinetic energy” depends on
the speed of the vehicle and on the weight of
the vehicle and of its passengers. The higher
they are, the more energy there is to be “ab-
sorbed” in the event of an accident.
The most signicant factor, however, is the
speed of the vehicle. If the speed doubles from
25 km/h (15mph) to 50 km/h (30mph), for
example, the corresponding kinetic energy is
multiplied by four.
Given that the passengers of the vehicle in our
example do not have their seat belts fastened,
in the event of a collision the entire amount
of the passengers' kinetic energy will be only
absorbed by the mentioned impact.
Even at speeds of 30 km/h (19 mph) to 50
km/h (30 mph), the forces acting on bodies in
a collision can easily exceed one tonne (1000
kg). At greater speed these forces are even
higher.
Vehicle occupants not wearing seat belts are
not “attached” to the vehicle. In a head-on
collision, they will move forward at the same
speed their vehicle was travelling just before
the impact. This example applies not only to
head-on collisions, but to all accidents and
collisions.
Even at low speeds the forces acting on the
body in a collision are so great that it is not
possible to brace oneself with one's hands. In
the event of a head-on collision, vehicle occu-
pants not wearing a seat belt will be thrown
uncontrollably forward and will collide, for ex-
ample, against the steering wheel, instrument
panel or windscreen ›››Fig.21.
It is also important for rear passengers to wear
seat belts properly, as they could otherwise be
thrown forward violently through the vehicle
interior in an accident. If a rear seat occupant
is not wearing a seat belt, they are not only en-
dangering themselves but also the occupants
of the front seats ›››Fig.22.
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