In our hypothetical collision, in a mere 1/10th of a second, Jimmy’s Toyota Camry will collide, crumple and come to a complete stop. The “crash impact weight” of the Camry will be absorbed by the larger cement truck.
Crash impact weight is computed by plugging the weight, velocity and the stopping time of an object involved in a crash, into a mathematical formula.
In our example, the Camry will have its own individual crash impact weight. Anything that is traveling inside the vehicle is also going to develop its own crash impact weight at the time of the collision.
This includes Jimmy!
When a driver or passenger is wearing their seat belt, at the instant of impact, their total crash impact weight is absorbed evenly throughout the entire length of the seat and shoulder belt system. Each of the hundreds of thousands of individual fibers that the seat belt and shoulder belt are sewn out of stretch to absorb a tiny fraction of the occupants total crash impact weight.
Make no mistake about it, buckling up and allowing your crash impact weight to be absorbed by the seat and shoulder belt system greatly improves your chances of surviving a crash!
Crash Impact Weight – How is it calculated?
In our hypothetical collision, when the Toyota Camry hits the cement truck, it will stop in 1/10th of a second.
In our hypothetical collision, because he is not wearing his seat belt, when Jimmy’s chest hits the steering wheel, his body will stop in 1/50th of a second.
The vehicle body of the Camry will crumple and compress before coming to a complete stop. Jimmy’s body will thud to a stop. This is why Jimmy’s body will stop five times faster than the Toyota Camry.
To determine the amount of crash impact weight that will be exerted on Jimmy’s body at the moment of impact, we can use the following equation:
| Weight of an object | X | Velocity | = Crash Impact Weight |
| *21 | *ST |
*21 is a fixed value that represents the pull of gravity converted to miles per hour/per second.
*ST is an abbreviation that stands for the “stopping time” at the moment of impact.
The stopping time for Jimmy is 1/50th of a second. 1/50th of a second is mathematically equal to .02, which is the figure we will use in the equation.
At this point, with all this mathematical business, are you beginning to feel like a slinky going down an up escalator? I apologize, but stay with me, this will soon be over, and this is important stuff.
Remember, crash impact weight is determined by plugging the weight, velocity and time of deceleration of an object into the equation.
Jimmy weighs 180 pounds, he is traveling at 30 mph, and he is going to stop in .02 hundredths of a second.
| 180 | X | 30 | = Jimmy’s Crash Impact Weight |
| 21 | .02 |
The figures in the equation above translate into: 8.57 X 1,500 = 12,855 Pounds
The equation has now told us, in our hypothetical collision, Jimmy’s crash impact weight is 12,855 pounds. With a crash impact weight of 12,855 pounds being exerted on Jimmy’s body at the moment of impact, he will most certainly be injured and could possibly be killed.
Some drivers think that without their seat belt on they will be able to put their arms on the dashboard and control their forward momentum at the moment of impact.
If you believe this is possible, simply ask yourself one question “Can I bench press 12,855 pounds?”
If your answer is not only “No”, but “Heck no!” then it should be crystal clear that the thousands of pounds of crash impact weight that are generated when a collision occurs cannot be controlled by you.
Always be sure to wear your seat belt and shoulder belt, so that at the moment of impact, these thousands of pounds of crash impact weight can be absorbed from your body as safely as possible!
