Question

When a car stops suddenly, the passengers tend to move forward relative to their seats. Why? When a car makes a sharp turn, the passengers tend to slide to one side of the car. Why?

Short answer

Due to inertia, the passengers tend to move forward when the car suddenly stops. and tend to move to one side when the car makes a sharp turn.

Step-by-step solution

Inertia

The inherent property of a body due to which it opposes any change in its state of rest or of uniform motion is called inertia.So when a car suddenly stops, the passenger’s lower body is in contact with the car, hence, stops with the car but the upper body still wants to be in motion and hence, falls in the forward direction

circular motion

Suppose a car rounds a sharp corner; the centripetal force makes the car travel in a curved path. Along with the centripetal force, the centrifugal force also acts on the body, radially outward. The lower body, being in contact with the car undergoes circular motion due to the centripetal force but the upper body resists this centripetal force due to inertia and hence, falls outward due to the action of centrifugal force.