>>>Here's something to make you think about speeding.
>>>
>>>120mph crash test
>>>
>>>http://www.youtube.com/watch?v=6dI5ewOmHPQ&feature=player_embedded#!
>>
>>Their logic seems a bit wonky. One car hitting a wall at 120 is not the same as two cars hitting each other head on at 120. Wouldn't the car have to do 240 to simulate that ?
>
>No. 1 car hitting an immovable object at 120 takes the full force, however, 2 cars travelling at 120 (assuming similar mass) would disperse the force equally between them, thus they would both take the equilivent of hitting the wall at 120 not 240.

That's correct, although in engineering parlance you're talking about "energy" (kinetic) rather than "force".

It's worth noting that energy varies as the *square* of velocity, so a car hitting the concrete block at 120mph absorbs 4x the energy of one traveling at 60mph.

>
>>In practice I'd guess a combined impact speed of 120 is *very* rare. Usually one or both drivers has braked pretty hard before the impact - the 40 mph test is probably a truer reflection of what happens in reality....

6dI5ewOmHPQ