1. Safety Operating Instructions
19
1.2.2
Why Wear Seat Belts
Protection from Seat belts
In case of crash, correctly wearing seat belts can
restrict the driver and passengers at proper
positions, reducing inertia of forward motion, to
prevent loss of control of motion and being ejected
out of the vehicle, and minimize injury due to
impact.
The seat belts can absorb most of the kinetic
energy resulting from a collision. In addition, the
crumple zones and other passive safety systems
can absorb the energy at the same time to reduce
the risk of injury further together with the seat belts.
Physical Principles of Frontal Collision
While driving, both the vehicle and the occupants
have energy (kinetic energy) which depends on
the speed and the occupants' mass. The larger
the speed and the mass, the more the energy
upon collision. In which, the speed is decisive. For
example, the released kinetic energy at 50km/h is
5 times that at 25km/h.
After a collision, the occupants not wearing the
seat belts still move forward due to inertia at the
speed before the collision, but the vehicle dose
not. Thus the occupants would be seriously
injured.
