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At what depth does an object that is normally buoyant actually sink? Can this happen?
Question Date: 2009-06-01
Answer 1:

The only reason why an object sinks or floats has to do with how its density compares with the liquid it is surrounded by

(density = mass / volume)

If the density of the object is less than the density of the liquid, the object will float. If it is reversed, the object will sink. Lets think about three different containers with a fixed volume filled with either air or water, or iron. For the air-filled container, since the density of air is less than water, the air-filled balloon will float. For the water-filled balloon, since the density of water inside the container is equal to the density of water outside the container, then the water will neither float nor sink, but remain submerged where the densities are equal. For the iron-filled container, since iron is denser than water, the container will sink.As you go deeper in depth, the density of water slightly increases. This means that objects that are normally buoyant at the surface, would remain buoyant as they go deeper under water (assuming the density of the object stays the same under the increased pressure). So to directly answer your question, there is no depth at which the object would sink as long as the density of water always remained larger than the density of the object.

Answer 2:

If an object is buoyant it will always be floating.This happens if the object is less dense than water, like an inflatable raft. If we wanted the normally buoyant object to sink, we'd either have to apply a force (like pushing it down with our hands) or change its density (like filling a balloon with sand instead of air).

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