In a car collision, the driver's body must change speed from a high value to zero. this is true whether or not an airbag is used, so why use an airbag? how does it reduce injuries

1. If I had my choice, I'd much rather crash into an airbag than a windshield.
2. When it inflates, it minimizes the distance you are going to travel. If a windshield is 2 feet away and you're heading right for it, an airbag would stop you before you hit the windshield by taking up the space between you and the (hopefully avoided) object.