It is not the speed at which you are traveling, it is how fast you stop that causes injury?

Question

could somebody explain this to me in terms of Newtons laws of motion and car safety features?

Answer 1

F = ma.

Mass is constant (you plus car), so acceleration is the only thing that contributes to force. If you accelerate quickly, you experience more force, if you accelerate slowly, you experience less force. Remember that acceleration can be speeding up or slowing down. The reason that higher speeds are more deadly is because you have so much more speed to lose, and a = dv/dt.  

Answer 2

Simply put:

It is NOT stopping that injures you, it is how much time you spend decelerating.

As this applies to car safety features, the most misunderstood is the seatbelt. The job of the seatbelt is not to 'stop' you or keep you from flying out the window (although it does that too) the job of the seatbelt is to expand sloooowly and slow you to a stop. (That's why it is webbed - to expand)

Think of this way: What is the difference between falling off a cliff to your death, and bungee jumping off the same cliff?

In both cases: you've fallen the same distance, and when you're done your velocity is zero. The only difference is RATE of deceleration, the difference between fun and death.