How Seatbelt Works – Part 1

When in motion, the driver and passengers are traveling at the same speed as the vehicle. If the vehicle suddenly stops or crashes, the occupants continue at the same speed the vehicle was going before it stopped. This happens due to inertia. Inertia is an object's tendency to keep moving until something else works against this motion. Things naturally want to keep going.

If a car crashes to a hard object, it is obvious that your inertia and car's inertia would be absolutely independent. The force of the object would bring the car to an abrupt stop, but your speed would remain the same. Without a seatbelt, you would slam into the steering wheel or go flying through the windshield. Just as the object slowed the car down, the dashboard, windshield or the road would slow you down by exerting a tremendous amount of force.

A seatbelt applies an opposing force to the driver and passengers to prevent them from falling out or contacting the interior of the car. Seatbelts are considered as Primary Restraint System (PRS), because of their vital role in occupant safety.