Quote:
Originally Posted by IamIan
Impact energy is the transfer of Kinetic energy ... they are not separate or different things.
You credited a larger mass itself for absorbing more impact energy:
Which is still incorrect.
It is the design of the structure that would allow it to absorb or not absorb the energy of the impact.
More mass itself ... will ALWAYS increases the energy of the impact ... mass itself does not absorb impact energy it adds more impact energy to the event.
Two vehicles of identical design expect Car A weighs more than Car B ... both vehicles experience the same collision event with a stationary object at the same speed ... Car A with it's greater mass will have more impact energy than car B ... This is just the way the world works ... KE=1/2MV^2 and F=MA ... A heavier , more mass itself always equals more energy and more force... what you wrote about heavier absorbing more impact energy ... is backwards.
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The fact that a heavier car has more momentum means it will take longer to stop regardless of what it hits. This means that the impact forces on the occupants will be lower, smoother, and applied over a longer period of time. The impact forces on what it hits are irrelevant.
Weight isn't the only thing that matters in safety just as safety isn't the only thing that matters in a car, however weight is a big determinant factor in safety.
I might add that there are insurance statistics that show a definite trend in an increase in fatalities with a reduction of weight per number of cars registered. In other words being able to stop and turn quicker doesn't overcome the better protection provided by a heavier vehicle
link to follow as soon as I find it.
edit link: not the one I was talking about but the summary pretty much wraps it all up
http://www-nrd.nhtsa.dot.gov/Pubs/808570.PDF