how to convert ft/sec into ft/lbs

[flash]

i was wandering if there is a website to convert it or wether it is just 100 ft/sec to 1 ft/lb

 

please help

 

flash

[jon78]

If that were the case...most air rifles would be supersonic!!

 

Not sure of any sites, but the ft/lb relates to the velocity AND mass of the projectle fired, i believe.

 

Jon

[Devilishdave]

The formula for kinetic energy for a bullet in motion is :

ENERGY (in ft-lbs) = .5 times (mass in grains) times velocity squared all

divided by a number to represent slugs in mass or 225218 or

symbolically:

 

ke = ( .5 * m * v ^ 2 ) / 225218 in units of ft-lbs.

 

So lets look at a typical hunting round for a .243 rifle

 

Bullet weight 100grains or 6.5 grams

 

Bullet vellocity in Ft per second 3000fps

 

1/2 x 100 x 3000^2

225218

=1998 ftlb

 

So lets try it for a .177 air rifle now pushing out a 8 grain pellet at 821fps

 

1/2 x 8 x 821^2

225218

=11.971 ftlb

 

And finaly lets throw a few figures in for .22, 13 grain pellet 644 fps

 

1/2 x 13 x 644^2

225218

=11.970 ftlb

Edited January 7, 2006 by Devilishdave

[kip270]

Try this site

 

http://www.firearmexpertwitness.com/customguns/calcnrg.html

[Gemini]

http://www.geocities.com/shiper_airgun/mat...tml?20067#twist

G.M.

[paulos]

the calculation i read in airgunner was:

 

((velocity squared) x pellets weight in grains)/450240

 

so a 14.3 grain accupel at 600fps:

 

600x600=360000

 

360000x14.3=5148000

 

5148000/450240=11.43ft/lb