weight is a force. weight = mass x gravitational acceleration. [F = m x a]

weight x speed = power. lol. since the unit is also Nm/s [i think LOL, dam i cant recall my physics stuff]

If you were looking for an actual measurement, wouldn't it be, lbs of pressure per square inch.  Coach Ruiz has a measurement tool that he uses by placing sensors on the heavy bag.  We usually are measuring kicks and by tweaking the technique you can see the improvement on the meter.  A kick that looks like you are really jamming the bag you find out is more push than penetration.  That bone crushing penetration generally takes less effort but your technique has to be spot on.  Soory, got carried away, my answer...lbs of pressure per square inch at the point of impact.

BTW...a rat has as much as 2500 lbs of pressure per square inch per tooth.  It is what allows them to chew through bricks, cement, cables, etc, etc. 

So what you all are saying is that my way of taking the weight of the person holding the bag and multiplying by the distance they travel backwards, times the coefiecient of friction of my mats is not an accurate estimate.... Man I hate when that happens!  I guess I'll have to switch over to the teeth method (as long as there not my teeth).

I measure my force rather crudely.

The magic question to me.  "Do they get up?  Can I walk away at a leisurely pace to call the cops, or do I need to run like hell?"

The equation is easy.

Left Jab + Side kick to knee + Left Jab + Right Cross + Left Hook + Right Hook = Unconscious attacker OR  Ranger running like hell for new horizons.   (Did I mention I'm getting a little old for hard running much as I prefer that over fighting?)  :D

Nice and funny,  Glad to see you around Ranger, long time no see.