Reply #14: Here's what 911physics.org has to say

[mikelewis]

http://physics911.ca/modules/news/article.php?storyid=14

"Let’s do some comparisons with weapons specifically made to penetrate strong buildings.

During WW 2, the British developed the “Tall Boy” Bomb

* http://www.members.aol.com/nukeinfo2/

It weighed 12,000 lb and could punch it’s way through 10 ft of steel reinforced concrete, when dropped from a great height ( a Lancaster bomber) Very impressive! The Pentagon may not be as strong, but the engine is alleged to have punched through nearly triple this width. The engine weighs about the same as the "Tall Boy." However the "Tall Boy" was travelling at several times the speed, and also contained explosives. And yet, somehow, it appears to be only marginally more effective, perhaps even less. All that engineering for nothing! If the penetrative performance of the 757 engine is anything to go on, it seems that the Brits would been better off to save their money and just drop big lumps of scrap metal. Not learning this lesson, they went on to develop the heaviest bomb of WW 2 , the 22,000 lb “Grand slam” bomb which could penetrate steel reinforced concrete to a depth of about 12 ft. In addition to it’s enormous weight and explosive power, it was dropped from Lancaster bombers, giving it great speed by the time of impact. The article mentions that the bombs were exceeding the speed of sound (760 mph), by the time they hit, but doesn’t mention by how much. That could be calculated if you knew the height at which the Bombers were flying.

* http://www.accessweb.com/users/mconstab/bombs.htm (also see previous link)"