Hit From Behind

In this clip, we see that seat belts and child seats not only protect you in a frontal impact, they could also prevent a tragedy in rear end collision. In this clip, the station wagon literally gets accelerated out from under the "kids" sitting in the back. They were at rest originally, and in the absence of a net force (from the seat belt) they remained at rest while the car they were in was accelerated by the net force from the car that hit them. Newton's first law can be a killer!

Crash footage from the National Transportation Safety Board