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cookiesdonniedarko-
Yes because E is proportional to the square of the velocity.
I understand the equation, I'm just not sure it's relevant. If you're hit by a vehicle at 40mph then you will very rapidly be accelerated up to 40mph regardless of whether it's a car, van, or HGV because they are all much heavier than you and so none of them will be slowed down appreciably due to conservation of momentum.
In any case this isn't relevant, since we have the direct measurements of the relationship of impact speed on probability of fatality that @dancing james posted.
ffm
Is it the v-squared part of the kinetic energy that makes the difference? Given the relative difference in mass between a pedestrian and a car isn't the pedestrian (or at least parts of their body) just accelerated, more or less instantaneously, up to the speed of the car when they're struck? Presumably it's this instantaneous acceleration and then deceleration when they then hit the road that does the damage.