Mike from Texas

I was playing around with the speed/ke calculating spreadsheet that I made a while back plugging in different arrow weights and such and as far as ke is concerned, at my draw weight/accessories/etc... 440 grains seems to be the optimal arrow weight for my setup. By that I mean when I go over 445 grains, my ke starts to drop. Does this mean my bow is most effecient with a 440 grain arrow and it is actually hurting me to go to a heavier arrow? At what point does it become fruitless to shoot a heavier arrow at the expense of ke & trajectory?

Coincedentially, my ACC 3-60s with feathers and a lighted nock with 100 grain broadheads weigh in at 442 grains and shoot 287 fps with almost 81# of KE.

ewolf

I kind of don't pay attention to KE. On the 3D course speed is what counts not energy. While hunting momentum counts and not KE. Momentum and KE will have a max and i would have to say that you found your max. What it really does for you i don't really know maybe someone can explain why KE matters.

Mike from Texas

I thought there was a website somewhere that would show your momentum in relation to ke. I had thought is was BowJackson's website but I didn't see it there.

ewolf

All that i know is momentum is what determines penetration. Not KE.

riverknight007

KE is the mass of the arrow times the velocity squared, this causes kinetic energy to depend more on the speed for a higher value.
Momentum, on the other hand is the mass times the velocity. Momentum is how difficult it is to stop the arrow, the higher the momentum, the better penetration.
Inertia is what makes an object difficult to stop. Inertia is how much an objects resists acceleration in either the positive or negative direction by an outside force, such as the friction of piercing an animal. Momentum is derived from this. It is proportional to both mass and velocity. Kinetic energy is not directed in any way, it is just a number, while momentum is a vector, meaning it has both magnitude and direction. I hope this helps.

riverknight007

It is a difficult concept to understand and I tried to simplify it as much as I could and tried to avoid the details. I have taken a few years of physics and different kinds of calculus in my short life and I still have to pause and think about the difference before I write it out. Both are important when talking about an arrow, but momentum is what you use to figure out the penetration because it is a vector and is directed into the animal's side, while the friction is working against it by pointing out the animal's side along the same axis as the arrow. The net force resulting from combining these vectors is what determines penetration (how long it takes for the velocity of the arrow to reach zero).

riverknight007

It is a difficult concept to understand and I tried to simplify it as much as I could and tried to avoid the details. I have taken a few years of physics and different kinds of calculus in my short life and I still have to pause and think about the difference before I write it out. Both are important when talking about an arrow, but momentum is what you use to figure out the penetration because it is a vector and is directed into the animal's side, while the friction is working against it by pointing out the animal's side along the same axis as the arrow. The net force resulting from combining these vectors is what determines penetration (how long it takes for the velocity of the arrow to reach zero).

Mike from Texas

DO you know the formula for figuring momentum? If the first part of the calculation is M x V what is the divisor?

Kanga

Mike.

There is all that on Bow Jacksons site

jca

your speed and k.e. is far greater than any animal on this planet can handle at any accurate shooting yardage!!! how do you think the indians killed moose ,elk,bear? not with a bowtech or a mathews!!!! only with sharp arrow heads,shot placement and skill to get inside a comfortable kill zone..get back to the KISS method and you'll be more successful in your hunts. technology is an advantage, not a mandatory factor. if you shoot a 350 grain arrow in the kill zone at 30 yards and a 550 grain arrow in the same spot at the same yards, both will get a clean pass through. only at longer ranges does heavy arrows with greater speed + more k.e. = any more advantage..i've got 2 velocity specialists in my family..don't get caught up in the marketing hype. shoot accurate at your comfortable range and hunt within that distance. isn't that what bowhunting is all about, getting close to you prey???