Archimedes principle states that "an immersed body is buoyed up by a force that is equal to the weight of the fluid that it displaces."
Things You'll Need
Small piece of wood
Non-floating object (e.g., a rock)
1Put a medium bowl inside a large bowl.
2Fill the medium bowl to the brim with water. Don't let it overflow.
3Place a small, floatable wooden object on a gram scale and note the measurement. A building block, a coaster, or a chunk of scrap wood will work provided that it’s small enough to fit in the medium bowl.
Do not confuse this with a regular scale. Grams are a unit of mass, not weight. Many cheap digital kitchen scales, for example, measure in grams.
4Place the wood in the water. It will float but some of the water will be “displaced” – i.e., will spill into the large bowl.
5Place another, separate container on the gram scale and note the measurement. Leave it on the scale.
6Remove the wood from the medium bowl, then remove the medium bowl from the large bowl. Be very careful not to spill.
7Pour the spilled water from the large bowl into the container on the scale and note the measurement.
8Subtract the mass of the container (Step 5) from the combined mass of the water and the container (Step 7). The result is the mass of the spilled water.
9Compare the mass of the spilled water with the mass of the wood (Step 3). They should be identical.
10Repeat the experiment with a non-floatable object such as a rock. Find its mass, place it in the water, and then compare that with the mass of the displaced water. They will not be the same. Why? Because the rock was too dense to float in the water; in other words, the water didn’t have enough “buoyancy force” (i.e., ability to float an object) to hold up the rock, which sank. Since the object could not remain buoyant, the buoyancy cannot equal the weight of the displaced water.