In article , Mr Macaw wrote:

two similar sized vehicles traveling at 30 mph that collide head-on is
equivalent to a collision of one hitting a brick wall at 30 mph.
...

Really?

really.

Which of the two comes out damaged, as it would if "hitting a brick
wall", and which comes out undamaged, as it would if only the other were
"hitting a brick wall" :-) ?

both are damaged.

Then you need a stronger device for the explanation. To make them identical,
you need a concrete bridge support which doesn't move at all.

i didn't say identical. i said both are damaged.

if a small car and an 18 wheeler truck collide, both will sustain
damage.

even a concrete bridge will sustain some damage if a car crashes into
it. it'll be minor but it won't be zero.