FPE general formula?

[Numb Nut]

Originally posted by robinghewitt
I think not

Trust me!

Furthermore, the imperial measure of mass is 'slugs' not pounds (which is really a measure of weight/force).

[mikebike]

Originally posted by robinghewitt
Works in Imperial just the same

Energy = foot poundals
Mass = pounds
Velocity = fps

It only gets silly if you insist on using bizarre units like foot pounds and grains

The beauty of the metric system is that it allows you to compare different forms of energy.

How many fpe is there in a portion of cereals?
How many fpe does a 60W bulb burn in an hour?
How many fpe do I produce during a training ride on my bicycle?

Et.c.......

[robinghewitt]

Furthermore, the imperial measure of mass is 'slugs' not pounds (which is really a measure of weight/force).

I think not

Rustram had better stop reading at this point A poundal is the force that will accelerate a mass of 1 pound at 1 ft/s/s

If you drop a mass of 1 lb it will accelerate at 32.16 ft/s/s so it is obviously being accelerated by a force of 32.16 poundals. That is where gravity appears to come into the equasion but doesn't really.

It's people who insist on using lbf for ballistics who muddle it all up. A slug is the mass that will accelerate at 1 ft/s/s when acted on by a force of 1 lbf. A ghastly fudge to make the maths work. This is why we divide by 450240, that's 225120 to convert grains to slugs and the half bit of 1/2 mv2

In metric, Joules = Newton metres. If you started using kgf instead of Newtons it would booger that up as well.

[Numb Nut]

Robin, I've looked up what a poundal is and have found that it is a unit of force, where 1 poundal = 32.17 pounds. Thus 1 foot poundal = 32.17 foot pounds.

This means that both our equations are equivalent, yours gives the measure of kinetic energy in foot poundals and mine gives the result in foot pounds. Sorted!