Pengy, having failed School Certificate twice (the second time with distinction) I can absolutely tell you that the answer to your question lays in the diminished area of impact and the rate of transfer of energy on impact. You heard it here first.
Now knowing that you are slow on the uptake, I will give you an example. Think of your hand as a gong. You put your hand on the floor, palm up. Rushy jumps on your hand with the heel of his boot from a chair (this is the 7-08). Your hand hurts (is dented) but is not pierced. Now Gibo (who is there or there abouts half of Rushy's weight) jumps on your hand from the same chair but Gibo is wearing his wife's stiletto (as he has a tendency to do on a Friday night) and he lands the heel right in the centre of your palm (this is the 243) and Bob's your nana, a neat hole in the hand.
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