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<p>[QUOTE=&quot;Bacchus, post: 44019, member: 759&quot;]<b>Archimedes Principle</b></p><p><br /></p><p>You’re correct, Archimedes Principle (AP) would have an effect on the weight a scale would measure if not measured in a vacuum.&nbsp; The pound of cotton would have greater volume than the pound of gold and thus would have more upward “pull” from the atmosphere than would gold.&nbsp; </p><p><br /></p><p>We don’t need to consider the same problem if the measurement was made underwater which has additional complexities (the cotton is absorbing water; the cotton, while solid, is not a solid block, so the water would “infiltrate” the outer volume of the cotton, etc.) which we might circumvent by stipulating the cotton is is contained in a vacuum-sealed virtually-weightless piece of shrinkwrap.&nbsp; </p><p><br /></p><p>This principle would not have any effect on the <i>mass, </i>and it would not have any effect on the gravitational pull on the gold or cotton, but I would think it would result in a force <i>countering, </i>the gravitational pull.&nbsp; I’m treating the gravitational force and the AP force as two different forces, the difference of which is the measured weight.</p><p><br /></p><p>For those not familiar with AP, think of a helium balloon.&nbsp; The balloon plastic and the contained helium have a certain combined weight.&nbsp; The air that the balloon <i>displaces </i> (the volume of the balloon) also has a certain weight.&nbsp; The balloon rises because the displaced air weight is greater than the combined weight of the plastic and helium, so the net weight is “negative”.&nbsp; Same thing with air bubbles rising in water.&nbsp; If the weight of the air was heavier than an equal volume of water,&nbsp; the bubbles would sink.</p><p><br /></p><p>I’m not a physicist, so if I have any of this wrong please correct me.</p><p><br /></p><p>Air at one atmosphere of pressure and 20 degrees C only weighs 1.204 mg per cubic centimeter, so I doubt if that is going to change the result of my original question.&nbsp; If I knew the density of cotton we could calculate the volume of a pound of cotton and multiply that by the density of air to determine the AP force and know for sure.[/QUOTE]</p><p><br /></p>

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