By: Natalie Weston
In order to maximize the chance of survival during a collision, many automobile-safety features have been implemented over the past few years. Pliable sheet metal and frame structures that crumple during impact are just one of the various safety precautions taken. Because when an object stops, or is stopped by a collision, the same change in momentum occurs no matter the size of the force or the time interval, these sheets of metal are critical to the passengers safety. The metal sheets not only absorb energy from the oncoming vehicle, but they also slow it down; and because the change in momentum is equal to the impulse, the longer it takes for a force to reach the passenger, the smaller the force will be. Another safety feature that greatly increases a person survival rate is the seatbelt. As Newton’s first law of motion states, an object in motion continues in motion unless acted upon by an unbalanced force. This continuity of motion, or inertia, causes those in a moving vehicle to continue to move forward after the car has stopped. However, if a person is wearing a seatbelt, than the seatbelt will act as the unbalanced force needed and the person’s motion will be stopped. Because seatbelts stretch, they extend the time interval in which a person in a moving vehicle is stopped. This expansion of time, much like with the metal sheets, prevents the person wearing the seatbelt to receive unnecessary injuries from it. Because impulse is equal to force times the change in time, the longer it takes for the seatbelt to bring a person to a complete stop, the less the actual stopping force will be. The person is still protected from flying out of their seat, and is less likely to be damaged by the seatbelt itself.
Assignment: Read the PDF, Surviving a Car Crash, and describe at least three safety features designed to increase chances of survival in a car crash, as related to impulse, momentum,