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Main Boards => PowWow => Topic started by: Prairie Drifter on January 30, 2010, 02:12:00 PM

Title: Momentum VS KE
Post by: Prairie Drifter on January 30, 2010, 02:12:00 PM
Since we all pretty much agree momentun is more important than kenetic energy, what would be some minimum momentum numbers for various game, ie;
deer,elk,moose ect. ?
Title: Re: Momentum VS KE
Post by: Earthdog on January 30, 2010, 02:38:00 PM
Who knows??

All I know is that KE is a theory,,,but momentum is like being hit by a truck,,,,,no need to be working out the result of that;^)
Title: Re: Momentum VS KE
Post by: Richie Nell on January 30, 2010, 02:52:00 PM
Earthdog,
Exactly right.  Momentum is real.  As mentioned before, a tuning fork has a pile of KE but not too terribly lethal.  But in the arrow projectile world all momentum is not the same.  Momentum with little mass but more speed is not the same nor as lethal as high mass and less speed.  The mass is the killer.  
So momentum numbers can be decieving if the mass is not there.
Title: Re: Momentum VS KE
Post by: Ragnarok Forge on January 30, 2010, 03:58:00 PM
KE and momentum are both measures of energy.  KE, is the energy stored in the arrow while in flight.  Momentum described how the energy is released and for how long that energy release lasts upon impact with your target.
Title: Re: Momentum VS KE
Post by: 30coupe on January 30, 2010, 04:19:00 PM
You need to impart enough momentum on the arrow to make it push a broadhead all the way through whatever critter you shoot. How much that is depends on the critter, the size and sharpness of the broadhead, the angle of the shot, and where you hit it.

On other words, there is no right answer to the question.

Practice until you can consistently hit the right spot. Practice until you can make your broadheads scary sharp. Practice until you can get inside of 20 yards of your quarry (we call that hunting here).

Then forget the numbers and go kill stuff!
Title: Re: Momentum VS KE
Post by: lpcjon2 on January 30, 2010, 04:29:00 PM
I'm stayen out of this for sure!   :coffee:
Title: Re: Momentum VS KE
Post by: jsweka on January 30, 2010, 05:43:00 PM
Like was said above, Momentum (mass*velocity) and kenetic energy (mass*velocity^2)are two measures of energy.  When one increases, so does the other.  I think it was some of Dr. Ashby's studies that showed a more direct relationship between penetration and momentum. I'd like to see the actual raw data so the geek in me could run my own statistical analysis.

I think the bottom line is that the more the better and there probably is not any minimum we can really throw out there for any single game species.  They are both good measures for comparing bows, but shot placement is still much more important than both when it comes to killing game.  E. Don Thomas had a good short article in TBM a couple issues back with his take it and broadhead design.