# Im confused



## Guillermo (Dec 24, 2014)

After i read the post created by Jacktrevally,i get a doubt:to hunt,it's best use joules as way to determinate the best ammo hunting,or momentum? Anyone of us knows a formula to calculate the blunt force trauma? thanks for your cooperation


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## zippo (Jul 9, 2014)

Both.


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## treefork (Feb 1, 2010)

Try an online calculator : http://www.1728.org/energy.htm


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## Guillermo (Dec 24, 2014)

Ok thanks for the info,but again,i have to use only momentum?


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## treefork (Feb 1, 2010)

Read these : http://slingshotforum.com/topic/16188-effective-hunting-setups/


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## zippo (Jul 9, 2014)

I use ft/lbs (or joules). But as i said, you can use both.


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## Guillermo (Dec 24, 2014)

Well,now yes i get it.Thanks for te info


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## Jacktrevally (Feb 14, 2011)

Hello my friend, did ya mention me name?

The product of momentum and energy gives you a vague indication, however if you apply Newton's second law of motion you'll get a firce in Newtons or KG if you divide it by g.

I've derived a formula which imples that

Force=Sqrt (2EM)/t

Simple stuff to derive, this will get you the force from an energy value in Joules!


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## Jacktrevally (Feb 14, 2011)

There is a way to calculate the blunt force on the target by using Newton's Second law of motion. E.g as below

Say ammo weighs: 10g
Time of flight: 0.25s
Distance: 18m
Velocity of ammo : 76m\s (about 250fps) when leaving the pouch
Velocity of ammo at impact:71m\s

Force= 3N

To mere mortals, a mass of 300g falling from 1m height equivalent under gravity

Simple innit?


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