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The Origin of Buoyant Force

publish date: 2026/05/18 21:36:1.615195 UTC

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What is the primary physical cause of the upward buoyant force experienced by an object when it is submerged in a fluid?

The difference in fluid pressure between the bottom and the top of the object.

The molecular repulsion between fluid molecules and the solid surface.

Atmospheric pressure pressing down harder on the surrounding fluid surface.

The horizontal pressure vectors squeezing the sides of the object inward.

Correct Answer

The difference in fluid pressure between the bottom and the top of the object.

Explanation

Because fluid pressure increases with depth due to gravity, the upward pressure acting on the bottom surface of a submerged object is always greater than the downward pressure acting on its top surface. This pressure imbalance creates a net upward force called the buoyant force.

Reference

Basic Physics: A Self-Teaching Guide

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Buoyancy