Most scientific and engineering applications use joules as the units; foot-pounds is an obsolete unit that is still used in discussing firearms because of a great deal of intellectual inertia.

E = M x V^2

or

E = M x V x V

to make this work for a bullet with it's weight known in grains the formula is:

E = Wb x (V x V) / 450380

E is energy
Wb is bullet weight in grains
V is the velocity in feet per second
450200 is 7000 x 2g
7000 = grains per pound
g = the acceleration of gravity (32.17)

PaulS

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stay safe and live long!

quote:

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Originally posted by russell6388:
What does foot-pounds of energy mean?

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I'm sure that the above answers are correct for those who have college and physics.

For us that didn't complete high school, foot-pounds (either energy or work) is a force thru a distance. ie, lift 1000 lbs up 1,000 feet and you have done 1,000,000 foot-pounds of work. The energy to push thru a distance is called 'potential' energy. This potential energy can be converted to heat, chemical energy, etc.

Since heat is the end result of many actions, it is interesting to me to note that 778 ft-lbs equal one btu. Fuel is also rated in btu's with gunpowder being near 2,000 btu's per pound. A 70 grain charge in a 300 winchester mag (1/100 pounds) then burns around 20 btu's which generates something over 3,000 ft-lbs of energy (kinetic or moveing) for about 4 btu's. 4/20 gives around 20% conversion of the chemical energy to kinetic energy of the moveing bullet.

JerryO