1 7 4 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 automob 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 crashes 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
greater the vehicle's weight, the more energy
that has to be "absorbed" in the 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
using 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. or 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-
sion 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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