Daewoo Kalos User Manual page 7

WHY SAFETY BELTS WORK!
Safety belts cannot work unless they are
worn and worn properly.
Vehicle occupants are injured if the
forces applied to the body's structures
are greater than the body can tolerate
without being injured. If a person's
body is stopped abruptly, the forces
applied to the body will be high,
whereas if the body is slowed down
gradually over some distance, the forces
will be much lower. Thus, in order to
protect an occupant from injury in a
crash, the idea is to give the person as
much time and distance as possible in
coming to a stop.
Imagine a person running at 15 miles
per hour (25 km/h) head first into a con-
crete wall. Imagine a second person run-
ning at 15 miles per hour into a wall
covered by a 3-foot (90 cm) thick de-
formable cushion. In the first instance
the person could be seriously injured or
even killed. In the second, the runner
could expect to walk away uninjured.
Why? In the first instance, the body hit
the non-yielding concrete surface and
stopped immediately. All of the energy
the sprinter built up was absorbed by
the structures of the body, not by the
non-yielding concrete surface. In the
second example, the body had exactly
the same amount of energy that had to
be absorbed as in the first example, but
it continued to move into the padding,
giving the body additional time and dis-
tance to slow down to a complete stop
as the padding absorbed the sprinter's
energy by deforming.
If a car crashes into a concrete wall at
30 miles per hour (50 km/h), the front
bumper of the car stops immediately,
but the passenger compartment stops
more gradually as the front structure of
the vehicle crumples. The belted occu-
pant is held to the seat and gains the
advantage of the cushion provided by
the crumpling of the front of the vehicle
and the stretching of the safety belt
webbing. That belted occupant's body
slows down from 50 km/h (30 mph) to
zero over a distance of 90-120 cm
(3-4 feet). That belted occupant also re-
mains properly positioned so that, if the
air bag deploys in a frontal collision,
SEATS AND OCCUPANT PROTECTION SYSTEMS 1–3
the occupant might never strike any
rigid structures in the vehicle. The
unbelted occupant receives no such ben-
efit. The unbelted person is not attached
to the vehicle and so that person con-
tinues to travel at the vehicle's pre-crash
speed of 30 miles per hour (50 km/h)
until striking a hard object at approxi-
mately 30 miles per hour (50 km/h)
and stopping abruptly. Even in a fron-
tal collision in which the air bag de-
ploys, the unbelted front seat occupant
remains at greater risk of serious injury
or death than the properly restrained
front seat occupant. (See "SUPPLE-
MENTAL RESTRAINT SYSTEM" in
the index)