The passenger suddenly bumps into their front having serious damage due to the law of conservation of momentum, the car that triggered it transferring the momentum to the passenger and the passenger receive the momentum so it will fly or bump into something due to the collision of an object.

Car safety features such as braking systems help reduce for during a crash by applying more friction from the brake to make the car decelerate or slow down, and avoid it from crashing any obstacles in front

Some parts of a car, such as the front and the back, made to crumple in a crash because it avoids the passenger or driver to get hit the hardest by the force of the car instead, the car takes the hard hit while the passenger will take the less hit. Thie momentum still transferred to the human, but the human will take less or least damage.

This affects the force on the body in respect to law of conservation of momentum wherein the car is in momentum then when slowing down, the car transferred the momentum to the body, creating less force on the body of the passenger and the passenger will be safe from crashing