ORIGINAL: GMMAT
TEmbry.....the MASS would help sell your rebar/bat argument more than momentum. Even using #4 rebar....they would weigh roughly the same. Anything over #4 and the rebar actually outweighs the bat.
I understand momentum as it relates to heavier objects traveling at the same speeds. What many overlook is......(relating this to a hunting arrow).....you can't get the same speeds out of a heavier arrow. At some point there becomes an "optimal" in both KE and momentum. I haven't met anyone versed enough to tell me what that is.....yet.
I only used rebar because it is thought of as stout....lets go with aluminum pipe then.
My whole point revolved around the fact that they arent traveling the same speeds. The lighter of the two will go faster, but it also wont knock the person down, meaning its travel path is stopped more easily...the heavier bat, will knock the guy out of the way and continue its path of swinging through. You are exerting the same amount of force with each swing, the speed is determined by the weight of the object...not how hard you are swinging.
It isnt that more speed equals more energy, which is how some guys (not implying you) look at it. The bow is putting out a set amount of energy at the shot, whether you are shooting a log or a feather. The lighter the weight, the greater the speed...BUT the heavier the weight, the more momentum...generally speaking.
momentum is an extremely simple formula, when looked at in Newtonian laws... P=mv. Mass x Velocity...the only two factors for momentum. Generally, more mass = more momentum when fired from equal initial forces simply because the mass increase is greater than the caused decrease in velocity..up to a point like you said. IMO, Momentum out weighs KE for arrow performance down range, but they usually go hand in hand.
In your case, yes it is as simple as adding 100-200 grns to your setup...it WILL give youmore momentum, how much could be figured by simple mathematics....whether it is worth it is up to you, the shooter. Your weight is more than ample for deer hunting though, especially with the numbers your bow can put out.
The thing I always think of, if mass and momentum arent important for penetration, why arent people using light arrow setups for grizzly, or buffalo, or moose hunting?