Since infants are much smaller and more fragile, they require more care and safety. This is where rear facing car seats come into play. When you get in a accident a car seat prevents the child from flying forward because the child is sitting securely the opposite way. It also prevents the child from getting slammed back because of the tightly secured seat-belt that covers practically the entire body. seat-belts increase the infant mortality rate by 71% as of 2012
Seat-belts are simple machines with simple jobs. That simple job however has important meaning to the well being of a person. Seat-belts are made up of 5 parts which may save your life in the future; The re-tractor, pillar loop, tongue, end bracket, and buckle. A safe seat-belt goes over your shoulder, across your chest, and over your waist. When you crash the belt is locked by the re-tractor which than makes it so that you are tied to the vehicle. it can only lock more unless you undo it. a good example of how it works is the same way as hand-cuffs. they can tighten but cant unlock with the key... or unbuckling in this case.
Green represents the percentage of crashes in which people wore seat belts. Red represents the fatalities with/without seat-belts over 14 years. As you can see the mortality rate is much higher in the years where more seat-belts were worn.
As shown in this example, this is what occurs when you hit an immobile object at 30mph. So when crashing your seat and body are flung forward, the seat-belt than locks putting large pressure on your waist area and across your chest. This than slows you down enough to safely hit the airbag which exerts a small amount of pressure over a larger area.
As shown in the figure above getting in a crash with an oncoming vehicle can be deadly with a seat-belt and especially without one. the man on the left is thrown forward because a object in motion stays in motion. He runs directly into the air-bag. At minimum he broke several ribs. However on the right, the man is held back by his seat-belt preventing him from flying out the window or into the dashboard because he has been tied to the car. He likely sprained something, may have gotten whiplash, and possibly a concussion.