On Apr 1, 8:35*pm, "fft1...@gmail.com" <fft1...@gmail.com> wrote:
> On Apr 1, 8:10*pm, jim beam <retard-fin...@bad.example.net> wrote:
>
> > why would they? *can you not see the difference?
>
> They were crashed into a cement wall at THE SAME SPEED, presumably.
> But if they were crashed into each other, the effective speed would be
> lower for F150.
>
> effective speed == speed relative to the center of mass of two
> vehicles

I'll try to explain this in layman's terms:

If you have a 3000 lb Civic crashing into a 6000 lb Ford Pickup head-
on, each traveling at 30 mph, then 0.1 seconds after the crash, their
combined mess will continue going where the Ford was going, but now at
10 mph (preservation of momentum). Therefore, Civic decelerated 40 mph
in the collision, and Ford only 20 mph.