alleryStart learning →Whether an object floats or sinks in a fluid is settled by a single comparison. Which comparison is it?
AIts volume against the fluid's volume
BIts average density against the fluid's
CIts total mass against the fluid's mass
DIts surface area against the fluid depth
Answer & Solution
Correct answer: B. Its average density against the fluid's
1. The buoyant force is the weight of the displaced fluid, and the object's weight is what opposes it.
2. For the same volume, the denser of the two substances weighs more.
3. If the object's average density is below the fluid's, the displaced fluid outweighs the object and it floats.
4. If the object's average density is above the fluid's, it sinks.
5. Total mass alone decides nothing, since a heavy ship floats and a small pebble sinks.
_Source: OpenStax College Physics (CC BY 4.0), Ch 11 "Fluid Statics", section 11.7 Archimedes' Principle_
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