Use Newton's 1st law of motion to explain how wearing a seat belt in a moving car could help prevent injury.

Answer 1

If the car was moving at 50 mph then you were moving at 50 mph.

If the car de-accelerates to a stop suddenly and there is no back force on you, you continue to move at 50 mph (first law)

Now the car is stopped and you are moving at 50 mph toward the windshield.

It would be better if you had something the de-accelerates you as the car de-accelerates.