Physics in the News
In March 2011 the New York Times ran a story about the significance of rear facing car seats. The article explained that a study demonstrated that children under 2 are 75% less likely to survive a serious accident if they are not facing backwards. The article gives the explanation that an infant’s head is large in relation to the rest of the body meaning that the supporting bones are not fully ready to stabilize the head. While the straps will often protect the infant’s body, when a severe impact occurs the baby’s head is likely to snap forward and cause acute trauma. With a rear facing seat the impact will be absorbed throughout the hard shell of the seat and the head of the infant will be protected.
The physics behind this research relates to the forces that will be pushed on the baby during impact. A head on collision with a baby facing forward will result in both extreme force being pushed on the fragile body as well as a potentially lethal head snap. The baby will be the primary recipient of all of the force. The hard shell of the seat will not prevent the forces from being exerted on the baby. With the seat facing the rear of the car the hard shell will be able to absorb and take the brunt of the force from the impact. The normal force of the seat pushing on the baby will be able to prevent the potentially severe head snap and the infant will suffer a less severe injury. Of course this would be reversed for a car that is hit from the rear.