FN 5.7 vs. 7.62x25

Joules and foot/pounds are essentially the same thing.

Joules and foot/pounds are both measures of energy and as such, one can convert from Joules to foot/pounds with a simple multiplication.

1 foot/pound = 1.35582 Joules

Neither foot/pounds nor Joules depend upon cross section.
They both depend solely on velocity squared and mass.

The ONLY difference between the two numbers is that one is calculated using metric measures of mass and velocity while the other is calculated using the English measures of the same quantities.

Neither measure is superior or inferior to the other in any way, nor does one number convey any more or less information than the other.
 
E=MV² regardles of units used. Ft lbs, Joules, pressed ducks or whatever.

Sam...my favorite 9mm is the 9X32R
 
Neither foot/pounds nor Joules depend upon cross section.
They both depend solely on velocity squared and mass.

The ONLY difference between the two numbers is that one is calculated using metric measures of mass and velocity while the other is calculated using the English measures of the same quantities.
Click to expand...

You're missing my whole point! Due to one being metric, it's easier to figure out how that works in relation to cross section. I'm not explaining this well I suppose, but I know what I mean anyway, lol
 
Dangus ... I think in the last part you 100% right ... we don't get the point. I, for one am curious as to what the point is ... I'm not being facetious, if there is an interesting way to look at different cartriges that I haven't seen and it has merit in physics for whatever reason (I don't want to talk about slug-acres per square fortnight just 'cuz the units map to energy!), I think it would be cool to hear about it. I was reading this through and have been trying to get the point. Oh well ... maybe just e-mail me if you feel like dropping it.
Saands
 
Dangus,

I guess I'm not understanding your statements about cross section, energy and calculating power.

Could you please post the equations?
 
I'll take a heavy 30 caliber chunk of lead over a light 22 caliber chunk of aluminum any day.
 
I'm just saying that I like metric, the rest of what I was trying to say is not important, I don't know how to explain it better than I am and I'm no math major so I have no clue what the proper terms are for all this. It's just that when .223 has a rated energy level that appears to be higher than .45 ACP, that doesn't make it a more deadly round against flesh at 25 yards. Calculating differences in surface area and mass and whatnot is more complicated than a simple matter of ft. pounds, and I am saying that to do those calculations, metric is a better system because everything works together so much more nicely in metric.

Does that make any more sense to you now?
 
Yeah,

Sometimes the English system is a real pain. The first time I started messing around with the K.E. Formula in English units I was surprised to find that the English unit of mass is 'slugs', not pounds. Furthermore, I was somewhat irritated to find that the number of pounds in a slug isn't a nice pretty number.

Happy calculating!

John
 
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