• PM_ME_VINTAGE_30S [he/him]@lemmy.sdf.org
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    8 months ago

    Actually, while you are correct about weight in general, the pound is legally defined as a unit of mass, which is exactly equal to 0.45359237 kg. Then, multiplying this pound-mass by 1 ft/s^2 gets you a pound-force which is a unit of weight. This implies that the pound-force is a derived unit in US Customary, British Imperial, and the other countries that agreed to the 1959 definition of the avoirdupois pound as a unit of mass.

    So while the earth would induce less pounds-force of gravity on an object high in the atmosphere than at sea level, the object would not lose pounds-mass, which is what pounds actually are unless the multiplication by 1 ft/s^2 is specified explicitly or implied. This is the case for any systems that use the avoirdupois pound.

    • LifeInMultipleChoice@lemmy.world
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      8 months ago

      No physicist would use pounds to define mass in the U.S. It is just wrong. Weight sure, but that same 1959 definition you mentioned did not mention it as mass from what I am seeing, rather weight - mass. I’ll see if I can find the actual accord to see if they list the terms used when proposed as it would be foolish to use pounds, next thing you know we would get a moon lander laying on its side. Haha. : )

      • PM_ME_VINTAGE_30S [he/him]@lemmy.sdf.org
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        8 months ago

        I couldn’t find the text of the agreement, but here is the notice from the US Department of Commerce based on that agreement. What’s interesting is that they discuss the relation of the 1959 definition to previous ones, and even back in 1893 the pound was standardized as a unit of mass.

        So it seems like, for at least 130 years, we have been “using the pound wrong” and no one bothered to correct us.

        • LifeInMultipleChoice@lemmy.world
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          8 months ago

          Haha, So that would require us to use pound and pound to have to different meanings. 1 pound of mass not equal to 1 pound of weight unless you are in the right circumstances haha. How dumb. Thanks for sending me that link by the way!