GMC Acadia 2011 Owner's Manual page 72

3-18 Seats and Restraints
The person keeps going until
stopped by something. In a real
vehicle, it could be the windshield...
or the instrument panel... or the safety belts!
With safety belts, you slow down
as the vehicle does. You get more
time to stop. You stop over more
distance, and your strongest bones
take the forces. That is why safety
belts make such good sense.