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.

W= fd
where f is an applied force and d is the distance over which it is applied. when a parachuting skydiver is at constant velocity, he is experiencing "terminal velocity", the point at which his acceleration down is canceled out by air resistance. that means that the resisting force of the air is equal to his weight, but in the opposite direction. with this, we can solve for the work done by the force.
w = fd
w = (92.0)(9.81 m/s^2) (325)
w= 2.93 x 10^5 j
the value for work in this case is positive because it is pushing up on the skydiver, who has a downward force of gravity.
therefore the answer is 2.93 x 10^5 j