Quote:
Originally Posted by Sterling
Ha! Knowing French does help!
FPS is a speed. Joules (If I remember what we talked about in Physics last year and correct me if I am wrong) is an amount of energy*release.
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That's correct, FPS is speed and Joules are energy.
In this case you can determine energy with:
(Mv² * W) / 450100
It's the standard equation for kenetic energy of motion: Speed in FPS (in this case Muzzle Velocity) squared, multiplied by the projectile's weight in Grains (1 gram == 15.432 grain). In this case we're also incorporating gravity (for simplicity's sake, we pre-calculate gravity as a constant*). The actual for formula is
(Mv² * W) / 2 G
The result will be in imperial Foot-Pounds (ft-lbs.) since we used imperial units to begin (namely FPS).
You can convert ft-lbs to Joules by multiplying by 1.356 (i.e., 1 ft-lbs. == 1.356 J.)
* gravity is generally accepted to be 980 cm/sec² on Earth. Since we're using FPS we have to convert that, which becomes 32.15 ft/sec². Similarly, we're using Grains rather than Pounds to calculate ft-lbs.: 437.5 grains == 1 ounce, 16 ounces == 1 pound (lbs). So:
( 437.5 * 16 ) * ( 2 * 32.15 ) == 450100