The following information should be helpful. Personally I think it works out to be a trade off. Slower speed/greater mass . . . greater speed/less mass. This has been an argument in rifle and handgun circles FOREVER. I concluded that is you shoot a deer in the hoof with a 375 H&H magnum it will keep going. Shoot one in the heart or lungs with a .22 it will go down. The moral of the story is and always has been if you are comfortable, handle your weapon well and shoot it acurately you are 99% there. If you can't handle it and shoot it well all the speed and mass in the world won't help you.

I would opt for the speed . . . if you have a quiet setup. I shoot a Mathews FX at 67# with 2213 XX75 aluminum arrows and 100 gr Thunderheads. My chronographed speed is 229 fps and the resulting KE is 56 ft-lbs. Not up there with some of the faster setups but hit right I get passthroughs every time; hit bad and I wouldn't.

Kinetic Energy
Kinetic energy is the energy of motion. An object that has motion - whether it is vertical or horizontal motion - has kinetic energy. There are many forms of kinetic energy - vibrational (the energy due to vibrational motion), rotational (the energy due to rotational motion), and translational (the energy due to motion from one location to another). To keep matters simple, we will focus upon translational kinetic energy. The amount of translational kinetic energy (from here on, the phrase kinetic energy will refer to translational kinetic energy), which an object has, depends upon two variables: the mass (m) of the object and the speed (v) of the object. The following equation is used to represent the kinetic energy (KE) of an object.
KE = ½ (m * v2)
where m = mass of object
v = speed of object
This equation reveals that the kinetic energy of an object is directly proportional to the square of its speed. That means that for a twofold increase in speed, the kinetic energy will increase by a factor of four; for a threefold increase in speed, the kinetic energy will increase by a factor of nine; and for a fourfold increase in speed, the kinetic energy will increase by a factor of sixteen. The kinetic energy is dependent upon the square of the speed.


Bowhunter