Exactly Moss. Its pretty much common knowledge. E = mv^2, That is, the energy of an object equals its mass multiplied by the square of its velocity. If you were to plug a set of integers from a table for the variables into this equation for mass and velocity you would see that energy increases exponentially with velocity.
However, since every cartridge has a maximum size, the goal is to have a cartridge with a bullet of adequate mass without compromising its velocity to achieve optimum energy.
As far as 9mm vs .40cal... My feeling has always been that more power equals more effective, so bigger is better. Thus, I have always leaned toward and owned the .40. Now that there has been all this talk of the 9mm being as effective and which is better or what not; I did the only thing I could think of...
Went out and bought me a new Kel-Tec P-11 9mm! Its Just for walking the dog and stuff though, not for serious shooting or home protection.
I still lean towards .40 and .45 no matter what any ballistics say.
Should I have split that in 2 posts?