Calculating Foot Pounds

[DMF38]

Does anyone know how to calculate foot pounds of energy? Suppose I'm shooting a 250 grain bullet from .45 Colt, and the measured velocity is 800 fps -- how would I determine the foot pounds of energy produced?

 

[The Bushmaster]

Bullet weight in grains X velocity squared divided by 450400 = ft lbs

 

[Sylvan-Forge]

From Lyman 48th edition

bullet weight in grains x velocity squared
divided by 450400 = ft-lbs

edit: lol, The Bushmaster beat me to it

 

[DMF38]

Thanks for the help!

 

[Clark]

As every school boy knows, energy is equal to one half mass times velocity squared.

The trouble is, guns are in the wrong units.




Energy = .5mVV= one half mass velocity squared
E = .5 [250 grains] [800 fps] 800 fps]
E= .5 [250/7000 pounds] [800 fps] 800 fps]
E = .5 [.0357 pounds] [800 fps] 800 fps]
Mass = [wieght]/gravity= .0357 /32.2 feet per second squared = .001109 slugs of mass
Es=.5[.001109 slugs][800 fps] 800 fps]= 355 foot pounds of energy


Or you can just multiply grains times velocity times velocity divided by 45 and move the decimal place to what seems right.

3555555.556

Is a pistol 35, 355, or 3555 foot pounds?
It must be 355 foot pounds.

It does not matter, as Nicole Simpson took 5 foot pounds to the throat and dropped.

 

[Jay29]

Go here:

http://www.handloads.com/calc/quick.asp