When a vehicle collides with another object - a tree, a wall or another moving vehicle, for example - it is stopped suddenly by the impact. However, anything not held down inside the vehicle will keep moving, and that includes the passengers. This happens because of inertia. Inertia is an object's tendency to keep moving until something else works against this motion.
Imagine that you're coasting at a steady 50 miles per hour (80.5 kilometers per hour). Your speed and the car's speed are pretty much equal, so you feel like you and the car are moving as a single unit.
But if the car were to crash into a telephone pole, it would be obvious that your inertia and the car's were absolutely independent. The force of the pole would bring the car to an abrupt stop, but your speed would remain the same. Your face might hit the windshield, the steering wheel or the back of the seat in front of you. Your ribcage might hit the dashboard. You could even be thrown from the vehicle. Your internal organs, too, will keep moving. Your brain would be compressed towards the front of your skull, and your heart, lungs and kidneys could smash into each other or into bone. It sounds horrific, and that's why we wear seatbelts. Seatbelts are designed to hold you into the car and spread the destructive force of the impact over the more resilient parts of your body, increasing your chances of avoiding death or serious injury in a crash by up to 50 percent.
However, seatbelts are designed for adults. They go across your middle and over the shoulder, applying most of the stopping force to your ribcage and pelvis. For a seatbelt to do this effectively it must fit correctly, and on a small child the seatbelt is simply the wrong size to do the job. Instead, a specifically designed child car seat should be used.
There are three basic types of child car seats, each designed for different ages (and sizes) of children:
- Rear-facing infant seats and convertible seats
- Forward-facing child seats
- Booster seats and backless boosters
First, let's take a closer look at rear-facing infant seats and convertible seats.