The Traffic Accident Reconstruction Origin -ARnews-

Re: Vericom VC2000

Ed Phillips (edphill@aol.com)
Tue, 27 Aug 1996 16:58:23 -0400 (EDT)

John

Let's not throw the baby out with the bath water. From your basic physics courses you know that approximating the area under a complex curve by use of a reasonable average value is a valid way of solving for that area. I grant you that the slope of the acceleration curve is constantly changing and if we were integrating finding the equation that describes that particular line would be daunting. Nonetheless many empirical scientifically controlled tests have shown that the slope of the acceleration curve may be reasonably approximated by a constant (an average friction value).
This statistical mean will allow a close approximation of the area under the curve. (For smaller curves - i.e. shorter distances-like skidding to a stop from some test speed.) It will also allow one to sum up the acceleration over the time period and compute the onset velocity. This method of averaging the area under the curve is used for force and impulse and many other complex aspects of a collision event. However when we move on to areas under a curve like those described by a parabolic function ( e.g. d = 0.5at^2 ) and we are looking at an immense area under the curve (like quarter mile data) then the approximations do poorly for the reasons you suggest the acceleration is changing at such a rate a couple of data points does not approximate the rate well.

Ed
Ed Phillips
edphill@aol.com

NOTE: You are reading in an archived session of ARnews. It is possible that this topic is still being discussed. To see if this topic is still active, or of there were any more recent posts on this topic, check later archives of ARnews.

If there is no current post, and you would like to add to this topic, link to the Current ARnews Discussion and begin a new thread. Be sure that if you are starting a new post that the thread title does not contain the abbreviation RE: Placing RE: at the beginning of a new post will confuse Hypermail and prevent others from answering your post in the future.

For example, to continue this discussion look for a thread titled

Vericom VC2000

If this thread does not exist in the current archive, you can begin another one by using that title.