Quote: At a combined impact velocity of a hundred miles per hour
Opposing velocity vectors aren't additive like that. Two people going at 50 mph toward each other will experience a crash of 50 mph. This is proven by thinking of two situations:
1) two cars crashing at 50 mph
2) a car crashing into a sturdy wall at 50 mph
Both will result in that car being stationary after the crash. In the case of the wall, it means the wall supplied a force equal, but opposite, to the car's force, leaving it stationary. The wall wasn't moving though. Therefore, in the first example, the second car is acting like a stationary wall, thus meaning that the experienced force is that of 50 mph.
/physics
You're lucky you don't live in Australia. On a daily basis I see shocking drivers...
"It is the mark of an educated mind to be able to entertain a thought without accepting it" ~ Aristotle
