What happens to unbelted vehicle occupants in a crash?

In a crash, unbelted vehicle occupants are significantly more vulnerable due to the lack of a safety restraint system. When a collision occurs, the vehicle quickly decelerates while occupants continue to move at the vehicle's previous speed until they are impacted by an external object, such as the windshield, dashboard, or front seats.

This phenomenon, known as inertia, means that unbelted occupants do not simply stop with the vehicle but are rather propelled forward until they hit something that brings them to a sudden stop, such as the windshield. This can lead to serious injuries or even fatalities, as they are at risk of striking hard surfaces inside or outside the vehicle.

While the other answers might suggest various scenarios of how occupants behave during a crash, they overlook the critical mechanics of safety and the impact of inertia. Unbelted occupants are not protected by seat belts and thus do not remain restrained in their seats or simply decelerate to a stop in conjunction with the vehicle. Hence, understanding the dynamics of a crash highlights the importance of seat belts, which are designed to prevent such dangerous outcomes.