As .E is proportional to the square of velocity, the more velocity the hand has, the

more energy will be transferred into the board. In the simplest possible terms, if the

board is infused with more energy than its structure can handle, it breaks. More

rigorously analyzed, energy transfer causes the board to dent. This process of

transferring energy is work (W). Work is force times distance (d): W=F· d. If the area

of the board that is struck dents a sufficient distance, it will break. Since the distance

it dents depends on the energy transferred to it and the amount of energy transferred

depends on the velocity of the karateka’s hand, a high-speed strike is most likely to

break the board.