CALULATING FOOT POUNDS OF ENERGY

[Hang-Fire Hank]

Folks: I have a chronograph, so I can measure velocity. Knowing that & the bullet weight, how do you determine foot pounds of energy? Hopefully, there's a relatively easy formula a non-science major may use.
Thanks, Hang-Fire Hank

NRA Life Benefactor
USAF Veteran
AZ Rifle/Pistol Life
CA Rifle/Pistol Life

 

[Hang-Fire Hank]

Folks: I have a chronograph, so I can measure velocity. Knowing that & the bullet weight, how do you determine foot pounds of energy? Hopefully, there's a relatively easy formula a non-science major may use.
Thanks, Hang-Fire Hank

NRA Life Benefactor
USAF Veteran
AZ Rifle/Pistol Life
CA Rifle/Pistol Life

 

[john traveler]

E = m v x v

Energy = mass times velocity squared

avoidupois units:
Ft-Lbs energy equals bullet wt (grains) divided by 7000 x velocity (fps) squared

 

[Paul5388]

It may be a little easier to use this calculator.

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

It also calculates the Taylor KO and momentum.

 

[Hoptob]

E (ft*lb) = 2.221*10^-6 * m (grain) * V² (fps)

 

[RidgwayCO]

Muzzle velocity squared, divided by 450436, times bullet weight.

For example, a 255gr bullet leaves the muzzle at 1400 feet per second:

1400 x 1400 ÷ 450436 x 255 = 1110 ft-lbs

The "450436" number corrects pounds to grains (7000 gr to a pound), and accounts for gravity (32.174 ft/sec*sec)

 

[Hang-Fire Hank]

Gentlemen: Thank you kindly for your info! I can "handle" several of those formulas. Very helpful! H-F Hank

USAF Vet
NRA Life Benefactor
AZ Rifle/Pistol Life
CA Rifle/Pistol Life
CCW Instructor

 

[jibjab]

Divide the velocity by 1000 and square it, multiply that by the weight in grains, and multiply that by 2.219.
1400/1000 = 1.4(2)=1.96 x 255gr = 499.8 x 2.219 = 1,109 ft-lb

 

[acl864]

If there's anyone out there who uses Excel to store their reloading and chrono data this formula will work to calculate muzzle energy in ft-lbs:
=(((A1*A1)*(B1/7000)/64.32))

A1 would be the column and row where velocity is posted in fps
B1 would be the column and row where bullet weight is posted in grains