What it shows
We have three 20 oz. soda bottles, one filled with water, one filled with sand, and one filled with air. A spring scale shows the water-filled bottle to weigh approximately 6N in air, and nearly 0N when it is fully submerged in a large container of water. Since gravity is still acting on the bottle when it is submerged in the water, there must be a force of 6N pushing up on it. This is the buoyant force.
We can do the same experiment with the bottle of sand. This bottle weighs roughly 13N in air, but when it is fully submerged in water it weighs 6N less. Even...
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