Answer
According to Newton's first law, an object in motion stays in motion unless acted on by a force. When a car stops suddenly, the passenger's inertia carries them forward at a constant speed until some force, such as friction from the seat or a force from a seat belt, acts to slow down the passenger. Note that this happens after the car has started to decelerate so it seems that a passenger is moving forward relative to the car.
Similarly, when a car turns sharply, a passenger's inertia keeps them moving in their original direction of motion until some force, such as from the side of the car or from a seat belt, acts on the passenger and pushes the passenger around the turn with the car.
Work Step by Step
According to Newton's first law, an object in motion stays in motion unless acted on by a force. When a car stops suddenly, the passenger's inertia carries them forward at a constant speed until some force, such as friction from the seat or a force from a seat belt, acts to slow down the passenger. Note that this happens after the car has started to decelerate so it seems that a passenger is moving forward relative to the car.
Similarly, when a car turns sharply, a passenger's inertia keeps them moving in their original direction of motion until some force, such as from the side of the car or from a seat belt, acts on the passenger and pushes the passenger around the turn with the car.
