Bullet Energy

[fingers80002]

Anyone have a formula for determing the energy of a round, at different yardages?

[djturnz]

Isn't just Mass times accelleration?

You want foot pounds of energy right?

Use this to get energy.
http://www.handloads.com/calc/quick.asp

As far as yardages, you'll need to know what the speed is at different yardages. To calculate it, you need coefficient of drag and all kinds of other physics crap that I have forgotten most of.

[Tomcat088]

DJturnz gave you correct information, in order to determine the kinetic energy you would need to know the speed it was going, how fast it's slowing down, and the other things like bullet weight, etc. You will also need to know the correct BC for your bullet, because that will also affect the drag and how the bullet slows down. Anyway, normally this is done with a ballistics calculator. Since you don't have one, I have a link for you that should get you pretty close to the actual energies. There's better ballistic calculators, but this one is still pretty good, and it'll give you what you're looking for. Hope this helps.

http://www.eskimo.com/~jbm/calculations/traj/traj.html

It's a little slow for a sec when it runs the calculations so don't rush it, it'll pop out the answers.

[fingers80002]

My chrono has a built in BC, just doesn't calc. energy.

[knight0334]

So long as you have the velocity at any given range and the bullet weight - you use the following formula for kinetic energy.


Energy = .5 * weight * velocity^2 / 7000 / 32.175

weight in grains
velocity in FPS

You'll just need to know the velocity at the differing ranges. Which you can get from one of those bullet drop/coefficient applications.

[fingers80002]

Thanks!
10 char

[VeryPrivate]

Unfortunately, bullet speed vs. Range is not a simple formula. Use the tables/calculators shown.

My favorite is http://www.biggameinfo.com/BalCalc.aspx

[daschnoz]

Simplified:

m = bullet weight in grains
v = velocity at impact in FPS


v * v * m / 450420 = ft/lbs