salo_t, nsr’s post above says it all. It is simple physics, F=mA. For A you have 500mph to 0 in a few milliseconds. That’s a big A. And we already know that m is very big — many, many tons. That means a really really really big F, as nsr has demonstrated. The reason the hole is smaller than the airplane is because aircraft are not solid objects, they are assemblies. The strongest parts (decks, bulkheads, etc…) are in the center and would penetrate more deeply. Also, the Pentagon is an office building, not a hardened bunker.
