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S a fet y belt s
_&.
WARNING
- Safety belts are the sing le most effective
means available to reduce the risk of se-
rious injury and death in a utomob ile acci-
dents. For your protection and that of
your passengers, always correctly wear
safety belts when the vehicle is moving.
- Failure to pay attention to the warning
light that come on, could lead to person-
al injury.
Why safety
belts?
Frontal collisions and the law of physics
Frontal crashes create very strong forces for
people riding in vehicles.
Fig. 198 Unbe lted occupants in a vehicle head ing for a
wall
Fig. 199 The vehicle cras hes into the wall
The physical principles are simple . Both the
vehicle and the passengers possess energy
which varies with veh icle speed and body
weight . Engineers call this energy "kinetic en -
ergy.''
The higher the speed of the vehicle and the
g reater the vehicle's weight, the more energy
that has to be "absorbed" in t he crash.
Vehicle speed is the most significant factor . If
the speed doubles from 15 to 30 mph (25 to
50 km/h), the energy increases 4 times!
Because the passengers of this vehicle a re not
us ing safety belts ~ fig. 198, they will keep
moving at the same speed the vehicle was
moving just before the crash, until someth ing
stops them - here , the wa ll ~ fig . 199.
The same principles apply to people sitting in
a vehicle that is involved in a frontal collision .
Even at city speeds of 20 to 30 mph (30 to 50
km/h), the forces acting on the body can
reach one ton (2,000 lbs. o r 1,000 kg) or
more. At greater speeds, these forces are even
higher .
Peop le who do not use safety belts are also
not attached to their vehicle . In a frontal colli-
s ion they will also keep moving forward at the
speed their veh icle was t ravell ing just before
the crash . Of course, the laws of physics don't
just app ly to frontal collisions, they determine
what happens in all kinds of accidents and col-
lisions .
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