For so many years, I've always heard that before purchasing your bow, you really needed to look at the Kinetic energy it developed.
Today, I am hearing that with traditional gear, the momentum of the arrow is actually more important than the overall kinetic energy it develops.
Momentum vs kinetic energy : What are your thoughts on this subject, I would be very curious to know.
Daniel
Kinetic energy without momentum is wasted energy.
It ain't about how fast the arrow leaves the bow, it's about how fast the arrow stops when it reaches the target... animal.
BOTH KE and M play a roll in how well and arrow will penetrate and object...which is why I believe the Kinetic Pulse formula is the most accurate in determing an arrows penetrating potential.
Ray ;)
Oh boy...here we go! :bigsmyl:
There really should NOT be an arguement with what Charlie and Ray have said. However I'll start looking for the corn and the oil. I still like it the old way!!!!!!
Thank you Charlie and Black Wolf : Guess you can't really seperate the two. Its funny however that some people only use the term kinetic instead of kinetic plus momentum.
Thank you :)
I've got my popcorn ready :bigsmyl:
Daniel
OK, I am hungry. What is the Kinetic Pulse Formula?
Scott
Please pass the salt.
Yep, they got it...To phrase it another way, The only output of a bow is KE, you decide if you want to use that KE in FPS or MO....You can go up on arrow weight and the KE changes little but the MO continues to go up and FPS goes down. The best of both worlds is the heaviest arrow that will give you the trajectory you can live with. That might be 8gr/lb for some or 15 for others. If that's not enough for the critters you are after, your only options is a better performing bow or more draw weight...O.L.
The more I hear about kinetic energy and momentum, the more I think that they are fictional theories fabricated by anti-hunters to get tradional archers to argue.
I'll bet if we spent more time shooting, and less time on the internet, that KE and momentum would not be such a big deal. I'll bet most people wouldn't even know what they were.
Mark
Thanks O.L., not only does it make sense, now I can relate to what some of the people say about this subject. It's always pretty confusing when you know a little about what is being spoken about and at the same time, you don't want to interupt the conversation. Just being polite but I'm happy I asked the question.
Thank you to all that posted on this tread. And please have yourselves a really beautiful day.
Daniel and Sylvie
Mark, If you think a 55# bow should shoot "harder" then a 45#, then you know what KE is and what it does for you. No biggy Daniel! :) ...O.L.
Daniel:
Just make up some "Scuds" and don't look back.
LOL
Pete:
Let's not go there now, ya know what I mean by that, don't ya, its like mentioning the word Popcorn in our home now, it has a totally new meaning...got to love that ATBA shoot :)
Daniel
QuoteOriginally posted by Charlie Lamb:
It ain't about how fast the arrow leaves the bow, it's about how fast the arrow stops when it reaches the target... animal.
I think that's the best explanation I've ever heard. :thumbsup:
And the lighter the arrow the faster it stops, unlike a momentum laced heavy arrow.
Easy to describe to a biker. What would you rather have you hit in the forehead at 60 mph, a fly or a june bug! :bigsmyl:
OL said it best.To get the most from any bow use a skinny string and load it down as much as you can with arrow weight to a trajectory you can live with.The bow only has so much to work with but doing it that way will get you all it has got to give. :)If that is not enough go shopping for a heavier bow. :D
QuoteOriginally posted by Killdeer:
Oh boy...here we go! :bigsmyl:
Killy,
Did you stir your coffee with your finger to sweeten it? :eek: :)
Bill
I did a search for Kinetic Pulse and came up with the following discussion. I deleted some of the filler to minimize the cut and paste.
ke = ( .5 * m * v ^ 2 ) / 225218 in units of ft-lbs.
The formula for momentum of an object in motion is momentum is equal to mass times velocity and it's unit of measure is the (slug ft/sec) or
symbolically:
momentum = ( m * v ) / 225218 slug ft/sec.
I have named this "volume of the crater" as the KINETIC PULSE or KILLING POWER (if you are a hunter) or for short reference as KP.
( KP can be considered a unit of measure for the physics purist. ) Therefore KP = kinetic energy * momentum or in symbolic formula using the units of physics:
KP = (mv)(.5mv^2)
Bill
PS Provide your own salt, butter and drink! ;) :)
KE is a measure of potential energy.
Momentum is a measure of energy applied in a single direction.
You pays your money and takes your chances, but I know which one I am going to bet on.
Jeff,
No matter which one a person thinks they are banking on, they are in fact banking everything on momentum, truth be known. I would rather have my longbow or recurve shooting a 10 to 12 gr/pdf arrow in the 170-175 fps range than an 8 gr/pdf arrow in the vicinity of 200-205 fps. Plus, I don't want my bow absorbing all of the KE, or in your terms PE, I don't get transferred to a light arrow!
Bill
LOL! and away we go. :)
OK, I can't restrain myself...
K.E. of a bow is 1/2 times mass times velocity squared.
Momentum is mass times velocity.
I looked up some test data taken by Pete Ward on a Cari-bow Perigrine and did a few calculations.
A 452 grain arrow went 187fps
A 702 grain arrow went 156fps
The K.E. is:
452 grain 1128 ft.lb./sec.sec.
702 grain 1220 ft.lb./sec.sec.
A difference of 7.5%
The Momentum is:
452 grain 12.07 ft.lb./sec.
702 grain 15.64 ft.lb./sec.
A difference of 22.8%
Same bow, heavier arrow has quite a bit more momentum and a little more K.E.
An interesting observation in this is that one would conclude that the K.E. should be the same for the two different arrow weights, but it is not. The heavier arrow has more K.E.
I think it may be that the heavier arrow is accelerated slower, but for a longer time, so it goes faster. Much like a dragster running a slower time often has a higher terminal speed.
Ain't physics cool?
Enjoy your popcorn folks. :D
Kevin out
:bigsmyl:
QuoteOriginally posted by Cupcake:
Same bow, heavier arrow has quite a bit more momentum and a little more K.E.
An interesting observation in this is that one would conclude that the K.E. should be the same for the two different arrow weights, but it is not. The heavier arrow has more K.E.
I think it may be that the heavier arrow is accelerated slower, but for a longer time, so it goes faster. Much like a dragster running a slower time often has a higher terminal speed.
Kevin out
Kevin,
Actually, the heavier arrow holds its velocity for a longer period of time because it has more MO-mentum! :D
Bill
I guess my post wasn't very clear.
I will take momentum of KE because KE is a measure of poetential energy that can be expended in many ways...noise, vibration, etc. Momentum only measures the energy stored and expended in a single direction. Energy expended in oscillation and noise are irrelevant.
Solution-Get a bow that shoots a real heavy arrow real fast! :knothead:
(http://www.fotosearch.com/thumb/csk/CSK151/KS2658.jpg)