Well, I was once a KE fan. I have since been converted.

I have done some research this past year and found some interesting information. I am an egineering student working on my master' s degree. Being able to utilize what I have learned has been excellent. Here is the low down.

Momentum is conserved. ALWAYS!!!!. To put this simply, momentum is always either transfered from one moving body with mass to another body with mass or it is " carried" by the moving body. Newton discovered this law and is one of the fundamental priniciples of the universe.

KE does not follow this law of conservation. KE can be transfered to another body in the form of potential energy, heat, or work.

There is another theory that relates to this topic and it is called the penetration theory. Very technical but in a nut shells describes the dependance of penetration on momentum.

Use bow jacksons calcualtor. Put in the numbers and see what happens. Play with a small light arrow at high speeds. Then try a heavy arrow at moderate speeds. You will see that the heavier arrow will maintain it' s momentum better than the lighter arrow.

I agree with Arthur P. Momentum is way under rated.