See why I had my doubts, I didn't think you were getting 100, ....83 is great. It calculates the amount of stored energy that your arrow has when impacting an object. It helps aid in penetration...think of it as power.....but KE is not the only force, there is momentum as well.

The calculation just gives some information pertaining to "power", in a bullet we might say, "Knock down power"..understand. I know that's simplistic but just an example.