Memes

45570 readers

1479 users here now

Rules:

Be civil and nice.
Try not to excessively repost, as a rule of thumb, wait at least 2 months to do it if you have to.

founded 5 years ago

MODERATORS

[email protected]

1158

ba dum tss (feddit.de)

submitted 1 year ago by [email protected] to c/[email protected]

50 comments fedilink hide all child comments

you are viewing a single comment's thread
view the rest of the comments

[–] erev 6 points 1 year ago (1 children)

Pounds aren't used for mass. They're explicitly a measure of weight. It's just almost always in the context of earth's gravity so the approximation to mass can easily be made.

[–] JustAnotherRando 7 points 1 year ago* (last edited 1 year ago) (1 children)

That's incorrect. They are, in engineering contexts, referred to as pounds mass (lbm) or pounds force (lbf) respectively. The US Customary Unit for mass is the pound (lb) (aka pound mass, lbm)

[–] [email protected] -2 points 1 year ago (1 children)

Neither of which were referenced by op. Lb is not a measure of mass.

[–] JustAnotherRando 2 points 1 year ago* (last edited 1 year ago) (1 children)

Again, that's incorrect. Pounds (Lbs) are the US measurement for mass. Feel free to provide a source to the contrary. I specified pounds mass vs pounds force because in an engineering space, it's worthwhile to be specific, but the Pound (lb) is all that is specified in any documentation as the unit for mass in the US system.

[–] [email protected] 3 points 1 year ago* (last edited 1 year ago)

I'm not the same person, but it seems like you're right. Pound (lb) is a unit for measuring mass. The same is true for kilogram. This actually surprises me to some degree, since it had not been clarified like this to me earlier:

In common usage, the mass of an object is often referred to as its weight, though these are in fact different concepts and quantities. Nevertheless, one object will always weigh more than another with less mass if both are subject to the same gravity (i.e. the same gravitational field strength).

...

Because mass and weight are separate quantities, they have different units of measure. In the International System of Units (SI), the kilogram is the basic unit of mass, and the newton is the basic unit of force. The non-SI kilogram-force is also a unit of force typically used in the measure of weight. Similarly, the avoirdupois pound, used in both the Imperial system and U.S. customary units, is a unit of mass, and its related unit of force is the pound-force.

Source: Wikipedia: Mass versus weight

I think we're probably confused of this because in common usage, we'll ask "how much does it weigh" and expect to get an answer in the unit of mass instead of force, just because the mass of the object defines the amount of force it will have in some given gravity condition.