Physics of karate chopping!

Ever since i saw my first Jackie chan movie (which i cannot remember off the top of my head), i have always been curious how a man, not especially strong and bulky with the muscles most football players possess, can break a cinder block in half with his bare hands. I previously thought that the cinder block would be too strong for even the most muscular man to even crack it let alone break it.

In this video, the person had two thick bricks stacked on top of each other and he broke both of them simultaneously with his bare hand. He put the very edges of the bricks on blocks so they would provide a very minimal normal force in the opposite direction of the applied force of the karate chop. Also, he aimed at the middle of the block with his applied force to where the center of mass had the greatest force in the downward direction provided by gravity. Therefore, when the man made contact with the block, the block was subjected to the force of gravity down and the applied force of his chop. With no reinforcement below the middle of the block, the person applying the force will feel a minimal normal force applied by the block itself. A very large force must be applied by the person chopping at the block but with the assistance of gravity and no reinforcement under the block, breaking a brick with bare hands is easier than it appears to be!