>Hi,
>
>>No, momentum is mass * velocity: the reason why a fist hitting a face does more damage to the face than vice versa - the fist, even though lighter than the face, because of its speed has a great momentum. The stationary face, although heavier than the fist, has no momentum.
>
>Huh? So if the fist was stationary and the head hit the fist at the same speed then the fist would suffer the most damage <g>

Not so funny aamof. Yes I guess the fist would come off worse, maybe broken finger bones. How about a head-butt? Both heads about the same mass but only the stationary one feels the pain, although action and reaction are equal and opposite.