this post was submitted on 07 Mar 2024
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Kilonewton? That would be a force and not a mass. For mass the standard unit is (kilo)grams.
LBS is Imperial Pounds which is a measure of Force and not Mass. That is why your LBS fluctuates based on gravity but your mass doesn't. So they are correct.
I see. Okay. Didn't know that.
Weight is a force and it's not mass. Weight is measured in Newtons.
We are not talking about the weight force here. We are simply converting pounds-mass to kg. If you dont believe OP meant the mass (whicg Im sure he certainly did) then aks him but when saying something weighs a certain amount then one is usually referring to its mass.
We were actually talking about Force, though. Pounds is a force, not a mass. I am OP and I meant force because I'm assuming the animal lived on earth. If I wanted to specify mass then I would have used Slugs, the Imperial unit for Mass.
Could you provide any source that states that a pound is a unit of force? Because the American National Standard Institute (here), aswell as Wikipedia and numerous other sources claim its a unit of mass.
The article you linked to does not mention at any point that LBS is a mass, or at all uses the word mass at any point throughout. In fact, it breifly at the end mentions "1 lb=0.45359237 kilogram" as well as "1 Newton=0.224809 pound force" which could indicate a difference between LBF and LBM distinctions.
It's commonly understood that you will weigh a different amount of lbs on the moon than on earth. Because it isn't a mass. It's a force of gravity.
There is also evidence in the form of lbs/in^2 being a common measurement, which would be completely nonsense in the context of mass.
I love educational threads like these.
Even though the original point was "using international standard units makes it clearer for everyone"
Yeah it is pretty fun.
Alright, lets look at the US Customary Units and their definitions. Here is the section called "Mass and Weight". As you can see, everything is defined in metric units of mass. You won't find even pound-force to be part of the Customary units. I couldn't find any source saying that pound (not "pound-force") is a unit of force. However, there was an agreement (I think in 1955) to define the pound in kg.
That basically implies that lb (pound, imperial unit) is a unit of mass and "pound-force" (non-imperial unit, part of the British Engineering Units) is a unit of force. Thus, pound (on its own) is a unit of mass, right?
British Engineering Units are not a part of the US-Imperial System, but since I never specified I suppose it's a good argument.
Did you take into account that earth was heavier millions of years ago? Also, you would have to specify where on earth it weighed that amount.
Anyway, pound is an imperial unit for mass, just like slug. The "pound-force" is not part of the imperial units, jut rather of the "English Engineering Units" that differentiate between pound-mass, pound-force, pound-foot and others.
"Pound" is not a unit of force in ANY system. If you really meant force (I doubt that) you should have used lbf. Anyway, noone cares how many Newtons of force the earth exhibited on that animal, all the metric-using people in this thread are interested in its mass. All scales used to weigh something display kg (or pounds), so units of mass.
The dino would need to be even lighter if the earth was heavier because the force of gravity would be higher, but in general differences in gravity across the earth's surface amounts to a rounding error. For example, you're probably looking at 2000 ish miligal from the top of a tall mountain to sea level difference in gravity, or .02m/s^2 difference.
From mountain to sea level yeah but the difference between Equator and North Pole is almost 1% because Earth is not a perfect sphere.
No, we don't refer to mass when weighing something. Measuring mass is quite hard, measuring weight is simple - just use scales.
In both the British Imperial System and the US Customary Units, a pound is a unit of mass, defined as 0.45359237 kg. In fact, all the definitions in the section "Weights and Masses" of the US Cusomaries are defined in either kg, g or mg.
A pound is a unit of force, slug is mass. There's also lbm (pound-mass) which is what I think you're thinking of, but that's not the standard
A pound is actually not a unit of force. At least not in the US Customary System nor in the British Imperial System. They both are defined as units of mass. Both systems define the standard pound as the "avoirdupois pound", a unit of mass. The US Customary System doesnt even include a unit of force.
"Pound-mass" comes from the "English Engineering Units" which differentiates between pounds-mass and pounds-force.
"Pound" is not a unit of force in any current system. Its the standard unit of mass (slug is also a unit of mass but usually not used). Feel free to provide any source that states that pound is a unit of force.
If you use a scale, the force acting upon the mass is calculated out such that you get a mass displayed.
And it will be a different number across the world. Because you can't measure mass with scales.
Depends on the scale and how it accommodates for the gravitational acceleration.
Lol.
Thank you, apparently most people here don't understand the difference.
Agree. The error is in the imperial system, there isn't a difference between weight and mass. The Weight depends on the gravity but the mass not. 240 Pounds Weight on Earth are on the Moon 40 Pounds Weight, but the Mass is still 240 Pound. Because of this in the SI system for the Mass is used kilogramm and for the Weight Newton (old kilopond)
But weight is gravitational force not mass. These are deeply related but not the same because us customary is based on pre Newtonian measurement systems
If you say that something "weighs" something, that's a description of mass, not weight, because the wording is from before a time when it was understood that mass and weight are different things.
All has been said that needs to be said, bloody pedant.
I was mostly just joking. Of course we use lbs as pseudomass. Fuck, we’ve moved to lbm vs lbf in America because mechanical engineers must be stopped and metricated by force if necessary. We’re a spacefaring species that’s advanced enough to have planetary gravitational maps, of course mass is what we should be using. But also weight as force is just kinda funny to use outside the myriad times you actually need to in engineering
Specifically LBS is a force, though. Imperial Pounds is not a mass measurement, so converting it would be a better equivalent to Kilonewtons.
This has the energy of an 11 year old who just learned what weight is in physics
Or a middle school physics teacher that barely knows what they're talking about.
Us customary defines the pound to be a unit of mass. Thats all you need to know.