SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/eng-floating-average-density

When will an object float in a surrounding fluid?

It floats when its average density is lower than the fluid's.

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  1. Its mass is always small
  2. Its material is always hollow
  3. Its average density is lower ✔

Why: Floating depends on average density, including any enclosed spaces. That is why a steel ship can float even though solid steel is denser than water.

Huh, didn't know that: A floating object settles until it displaces a fluid weight equal to its own weight.

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The steel ship stayed positive by keeping its average density down.
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References

Answer: Its average density is lower. Floating depends on average density, including any enclosed spaces. That is why a steel ship can float even though solid steel is denser than water.

  1. OpenStax University Physics Volume 1, Archimedes' Principle and Buoyancy openstax.org/books/university-physics-volume-1/pages/14-4-archimedes-principle-and-buoyancy
    If an object's average density is less than that of the surrounding fluid, it will float.
    Checked 2026-10-10.

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