The rocket engine specs I’ve seen are pounds of force or specific impulse.
“The rocket engine specs I’ve seen are pounds of force or specific impulse”.
Correct. These I mentioned were thrust, so should have been in pounds.
If you had a 34 pound weight at the end of a 1 foot rod, that was twirling around in a circle and whacked something each revolution at 1300 BPM, I suppose you might measure that in foot pounds and BPM .
I guess. At a rate of 1300 rev per min or 22 rev per second at a radius of 1 ft, that is a speed of 2π(22) = 136 ft/s. The linear momentum at impact would be 34(136) = 4630 lb-ft/s
Impulse depends on the time it is in contact. if that is 0.01 sec (at a guess), then the impulse would be 46 ft-lb.
So you could consider the 34 ft-lbs an impulse measurement.
But I played fast and loose with US units of mass and force, as both are sometimes measured in pounds, skipping the poundal and the slug, both of which confuse me.
OK folks, from rockets and math back to cars. All I can say is life changed with the invention of the pocket calculator. I keep one in my go bag in the car all the time.
Get a smart phone - Calculator is one of the built in apps.
I wish I had pocket calculators when I was in high-school. My AP Calc and AP Physics would have been a lot easier. Slide Rulers were great, but a calculator was so much easier.
Yup!
You beat me to it, Mike.
Even though it took me a few weeks before I started using that app, it is really handy for use in stores, restaurants, and other places where you want to do a quick calculation.
And, when I am in the car, if I don’t feel like taking my phone out of its holster, the info center on my car has a built-in calculator. That function is “greyed-out” when the car is moving, but as soon as I have stopped, I can display a calculator on the 6.5 inch screen.
No need to carry extra calculators in the 21st Century!
I have a calculator on my phone, but I prefer something with actual buttons to push.
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Potential impact energy of a fired bullet is calculated with bullet weight and speed and expressed in foot/pounds. Torque specs for motor vehicles is expressed in pounds/feet. I researched it years ago and the terms were supposedly interchangeable and thought to be another case of English English verses American English.
No, torque is in ft-pounds (or pound-ft, same thing). NOT pounds per foot. More correctly, it is in newton-meters.
Energy of a moving object (Kinetic, not potential) is in joules or BTU. Potential energy is in the same units.
edit: kW-hour is another unit of energy, as is calorie, electron volt (eV), and tonne of TNT
Who would have thought this is as controversial as putting Romex in conduit?
Hmmm… I don’t know 
…
… perhaps the same folks that thought this was a discussion answering the question,
“What is wrong with my brakes ?” 
CSA
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I was not sure how to spell it. Having heard it spoken as pounds/feet I took my best shot.
George’s demolition hammer specs sent us on the path of derailment and since none of our engineers drive trains it could not be avoided.
Or inch ounces, or kgf-cm.
It doesn’t matter how you describe it. What’s important is understanding that it represents a specified force applied a specified distance from the rotating axis. If you had a long enough wrench and a big enough bolt you could even describe it as pounds per yard.
On my Toyota design documents it’s represented as
N-m, (Kgf-cm, ft-lbf)
That isn’t what most people are used to, but that’s the way they specced it.
You are correct of course. I was commenting on the lb/ft, which is pounds per foot or force divided by distance, totally wrong.
I’ve seen and heard torque described multiple ways.
Fact is, five pounds applied one foot from the axis is the same as one pound applied five feet from the axis. What really matters is understanding what it all means.
you are correct, of course. torque is force multiplied by distance, as simple as that.
What I object to is torque described as force divided by distance. That is totally wrong.
I think we have beaten this to death…
No pun intended? lol … I think the foot-pound & beats-per-minute specs for comparing demolition hammers has been pretty much justified by the discussion above. It’s sort of like how engine engine power is measured as a product of torque (in foot pounds) and rpm. 100 foot pounds * 1000 rpm = 19 HP. The power of the electric motor running the demolition hammer must be proportional to a product of the foot-pound spec and the beats per minute spec.
Looking for that emoji of the dead horse being whipped, but alas cannot find.