Newton's first law of motion states that an object in motion tends to stay in motion unless an opposing force stops it.
since you are in motion while riding your car, If you suddenly run into some kind of obstruction, your body will continue to move in the direction it was going. Seat belts are very important because they're there to stop you. Not wearing seat belts would probably cause injury or death because, you could go right through your front window unless you have them worn.
