According to the 1st law of Newton or Law of Inerta:Any body if in rest or is moving with uniform velocity (zero acceleration) will continue doing it so as long as no force acts over it.
During a head on auto colloision like when we are in a bus or a car,if the driver takes a break or a turn or even in accident,our body is in inertial state as long as not disrupted by any Force.
Inthis case,the passenger on the front seat is moving with uniform velocity due to inertia and will stop when hit by the car's dashboard or anything like that!
