Answer:
Newton law of inertia.
Explanation:
Newton first law states that if any object is in the motion or is in the state of rest then it will remain in that state till the external force is applied on that object. Inertia is the main reason of having seat belts and air bags in the car.
In this case, when seat belt trapped into the passenger than passenger experience same state of motion as car has.
When the car experience any kind of the collision then the car will stop abruptly. In this case seat belt and air bag will help in stopping the motion of passenger in the forward direction.
Therefore Newton's law of inertia is illustrated in test with seat belts, crash dummies, and air bags.
