Being in a crash at 30 mph has the eqivalent force of being dropped off a four story building?

Not exactly - a 30 mph crash alone cannot determine the severity of the crash - the damage to a human body in a crash is largely the factor of time it takes from the 30 mph velocity to zero - I figured this out a long time ago for a physics exercise and don't remember exactly the numbers but a rough estimate if my memory serves me 20 years later was - a thirty mile an hour collision to zero in one second created somewheres on the magnitude of 25 + G's

• and I remembered ballpark numbers back then because I also

learned that somewhere just over 9 G's all the major arteries get ripped from the heart and you die instantly - I remember this because my then favorite uncle was killed in a 60 mph crash when a drunk went through a stop light - and the part that a 12 year old kid couldn't understand was that he didnt have an external bruise on his body - so this story has been recanted numerous times to nieces, nephews and even now my own son as he started driving. - and just for a side bit of information - for every fractional part of second longer you gain in your deceleration your survival rate goes up logarithmically - that is why cars today that appear to have crumpled horribly in a crash were actually designed to do just that - all while the car is crumpling and bending, it is absorbing the energy of the crash and buying your body precious seconds to slow down.