kinetic energy

[PAPA BEAR]

can someone please tell me what the formula is to figure out my kinetic energy please...i'm shooting a 650gr arrow at 61pounds at 190 fps...i keep coming up with 51 pounds.that sounds wrong for that heavy of an arrow doing 190...thanks  

[lpcjon2]

I thought trad would be simpler...LOL Can you google Kinetic energy it should give you the formula

[PAPA BEAR]

just curious      

[lpcjon2]

This is what I found.

The kinetic energy of an object of mass m traveling at a speed v is mv2/2, provided v is much less than the speed of light.

you can use this link

 http://en.wikipedia.org/wiki/Kinetic_energy#Calculations

[Running Buck]

Speed times Speed times weight divided by 450,240. This will give you the kinetic energy of the arrow at the distance you measured the speed at. Most shoot at three or four feet away from the chronograph.

[Ricker]

I found a kinetic energy calculator for you to look at.

 http://www.dewclawarchery.com/Kinetic_Engery_Calculator-a/157.htm

[wingnut]

52.1 and .548 momentum

Pretty dang good for a stickbow.

Mike

[khardrunner]

I'm not sure why you would want to calculate KE. Maybe like me you are a nerd :-) . Either way, the more important calculation when considering how much damage an arrow will do is momentum. Good luck and I hope you find what you are looking for!

[PAPA BEAR]

i was just curious to know thats all.i knew that gr arrow and speed would be good elk medicine.

[PAPA BEAR]

thanks wingnut

[Don Batten]

So Help out a poor dumb country boy, which is better, faster or heavier? I know the pingpong ball and golf ball in  the snow deal. I'm asking, when does a faster lighter arrow, out perform a heavier slower arrow? There's got to be a point where lighter is better. Just curious. Don

[PAPA BEAR]

i think the heavier arrow will always be better unless you're shooting a very slow bow maybe.not sure about that one though,maybe someone will chime in.

[wingnut]

It's a balancing act.  You always want enough broadhead and arrow to get an exit wound on your animal.  For me that is usually about 10-11 gpp and a top end BH.

Going Moose hunting in a month and we are shooting 720 gr arrows with Abowyer Brown Bears.  I'm restricted to no more then 50# so my bow is 52 @ 30.5.

Mike

[acadian archer]

good luck

[onewhohasfun]

If you double the weight of your arrow, you lose only one half of your velocity. So in answer to Dons  statement that " at some point lighter is better", Lighter will never have more momentum. I think 650gr. arrow going 190fps will shoot thru 2 elk.

[PAPA BEAR]

yep it sure will.gonna have my hardened snuffers guidin the way.

[ChuckC]

Mike. .  no MORE than 50 # ?   Hmmmm  well it is probably 50 # at 29"   there ya go !
ChuckC

[screamin]

I've have heard from a reputable source, that in order for a 650 gr arrow or above to be the most effective. It has got to be going at least 155fps. Never tried it personally, but I do trust the source.

[wasapt]

to calculate kinetic energy... take your arrow speed in fps, squared..
210 fps x 210 = 44,100
divide by 450,240 ( a constant ) 44,100/450,240 = .09794
then multiply .097794 x arrow weight 515 = 50.44 KE
 
Ashby's formula for momentum is written in TBM April/May 2007. On page 50, he states an arrow must meet or exceed the threshold of 14.8 pd-feet/sec of momentum . He has a chart of arrow weight and the correllating speed in fps to have the necessary momentum.
550gr @ 189 fps, 600gr @ 173 fps, 650gr @ 160 fps. Hope that helps

[acadian archer]

download the easton shaft selector program 9too stiff in my experience) but it does have a KE calculator