Nano Cushion - Collision Impact reduction

Have you ever thought what is the simplest logic behind seat belts and safety crash bags that are installed in your cars? The logic behind them is that they will "elongate" the time of collision by a fraction of seconds, there by reducing the impact, the time taken to transform the kinetic energy to potential energy.

Imagine someone falling down from a 3 rd storied building - if he has directly hit the ground after coming down whole of 35 ft, he is likely to die. What if he hits a tree branch at around 24 ft from ground, then hits the balcony at 12 ft, a moving trolley 4 ft from ground before he hits the floor - he is much more likely survive but ofcourse with crushed bones. What happened to him was that the difference of potential energies at 35ft to floor has been distributed in series of impacts instead of one big thud. In world of finite element analysis, they multiply these impacts by an order of million and there by giving a smooth ride instead of a fall to the guy who jumped out of the window.

Coming back to air bags, this is achieved through incremental increase in volume of air (if the bag is taut, then it serves no purpose of a cushion) there by reducing the impact. Instead of this singular and linear non-dynamic way of securing crashes, there gotta be a dynamic way of designing car safety. My design would resemble something like a chain saw, where the teeth can close and open and that can be controlled using a timing device.

1. When all teeth are closed, then the surface is flat
2. When all teeth are open, the surface is rugged, like a saw.

This device is fixed underneath the car seat - the seat is firmly coupled to a plank that is edged on the bottom. Essentially, when the saw beneath is in "open" state, the teeth of the seat and teeth of the saw clasp hard and holds the seat tight from bottom. When the saw is in "close" state, the seat can slide back and forth. During headlong crash, the car seat would move forward, so the objective is to make sure that the seat stays "dynamically" stable while the crash is happening.

It can be achieved in following manner. The saw should be motor powered (think electronically controlled motor) to rotate in direction opposite to motion of the seat. If the seat is moving forward at a speed of 10 mph, then the saw goes in open state and moves it back at 12 mph and goes into "close" state. By a series of "open"-"close"-"open"- "close", the seat is let to move forward and backward. If this is done a million times within a second, it would makes the seat to be essentially stable all through crash - there by creating a nano mechanical cushion engine.