Why foot/pounds?

[ironman andy 0]

The question that I am about to ask has been puzzling me for some time now.

Why do we use Foot/Pounds as a measurement of pellet power?

As an engineer, I know Foot/Pound, (Newton/ Meters in metric), is a measurement of Torque!

 

WARNING GEEK STUFF BELOW!

In physics, a torque is a vector that measures the tendency of a force to rotate an object about some axis (center). The magnitude of a torque is defined as force times the length of the lever arm. Just as a force is a push or a pull, a torque can be thought of as a twist.

The SI unit for torque is Newton meters (N m). In U.S. customary units, it is measured in foot pounds (ft/lbf)

 

So, how can that be relevant to a pellet being projected from a muzzle of a gun?

Surly the velocity (feet per second) is the relevant measurement, so why is Ft/Lbs still used?

It is like me measuring a length of steel and saying it’s 27degrees Celsius long!! It doesn’t make sense.

If a power measurement is needed then I think it should be Joules!

I feel better for getting that off my chest, tell me your thoughts.

 

Ironman

[SEAN3513 7]

air rifles are rated in ft/lbs and joules.............i think but dont quote me 12 ft lbs = 15 joules.

 

i know it dosn't answer your question but m sure someone will offer more info in due course.

 

all the best

 

sean

[shaun22 0]

As an engineer, I know Foot/Pound, (Newton/ Meters in metric), is a measurement of Torque!

............................

If a power measurement is needed then I think it should be Joules!

 

But isn't 1 Joule the same as 1 Newton/Meter? And aren't ft/lb, joules and N/M all measurements of translational kinetic energy?

[Coney 3]

Could be wrong but always thought 16 joules = 12 ft lbs.

[SEAN3513 7]

i stand corrected..................wasn't dead sure!!!!

 

thanks coney

[SEAN3513 7]

just for the info..........ft/lbs x 1.355817 = joules

 

therfore 12 ft/lbs = 16.269804 joules

 

no i'm not an anorak, just like to understand stuff

 

( coney, top of the class)

 

all the best sean

[Coney 3]

just for the info..........ft/lbs x 1.355817 = joules

 

therfore 12 ft/lbs = 16.269804 joules

 

no i'm not an anorak, just like to understand stuff

 

( coney, top of the class)

 

all the best sean

 

 

Cheers mate.

[grasshopper 0]

I never thought much about that before!

 

very interesting! :-)

[ironman andy 0]

I can see my error in thinking ft/lbs only being tortional energy

 

Here is the wikipedia definition of a Joule:

 

"One joule is the work done, or energy expended, by a force of one newton moving one meter along the direction of the force. This quantity is also denoted as a newton metre with the symbol N/m. Note that torque also has the same units as work, but the quantities are not the same. "

 

Cheers to all

ironman.