[masraum]

Originally Posted by javadog

That weight doesn’t change, the buoyant force just opposes it.

I agree and disagree.
The mass doesn't change. Yes, the bouyant force is another force acting on the object in the opposite direction to the force of gravity. The weight will change by some (very small) amount based on "altitude" (whether it's up or down).

But certainly if you try to measure the weight of the object, it will measure differently at the bottom of the ocean than it would in a hole in the ground that was as deep as the bottom of the ocean due to the bouyancy.

The first definition of weight on the Merriam Webster website is, "the amount that a thing weighs." If you then check the definition of "weighs," the first definition is "to ascertain the heaviness of by or as if by a balance."

Using those definitions, the bouyant effect of a liquid on an object would affect the weight of the object. If you consider weight to be "mg" (mass x gravitational constant) and you know the mass (no need to measure it) then yes, the weight using that formula would not change unless either the gravitational constant changes or the mass changes.

Technically, our weight probably changes whether it's midnight on a full moon or midday on a new moon because the gravity of the moon does impart some (albeit REALLY small) force on us. Clearly there is some impact from the gravity of the moon or we wouldn't have tides. Just another funny to consider datapoint due to forces.