Well, kind of. Actually what I do understand is that the KE of the arrow (or any other projectile) is what gets it to the target. On the other hand, it is momentum (p=mv, where p = momentum) is what drives the projectile home. While p and KE are related (they are both functions of mass and velocity) is the MOMENTUM of the arrow that drives it into the deer, allowing the broadhead to do it's work. I hear about KE all the time, and I understand the significance thereof. However, I never hear about the significance of momentum. That is unfornatute and momentum is that which causes pass through, or no pass through, bone breaking etc. Certainly penetration is not quite that simple, as many things contribute (diameter of the arrow, coefficient of friction between the shaft and the target, and all that stuff), but again, all things being equal, it is momentum that is the real deal behind penetration. Momentum = penetration, penetration = dead critter. Velocity is important is more important in getting the projectile to the target, but mass is equaly important when it comes to penetration...