Understanding the Origin of Buoyant Force Explanation

The question asks about the physicist responsible for explaining the existence of buoyant force. Buoyant force is the upward force exerted by a fluid that opposes the weight of an immersed object. Understanding who first described and quantified this fundamental concept in physics is key to answering this question.

Identifying the Physicist Behind Buoyancy

Let's examine the contributions of the physicists listed in the options:

• Archimedes: A Greek mathematician, physicist, engineer, inventor, and astronomer. He is credited with discovering the principle of buoyancy, often referred to as Archimedes' Principle.
• Blaise Pascal: A French mathematician, physicist, inventor, writer, and Catholic theologian. He formulated Pascal's Law, which concerns pressure in fluids. While related to fluid mechanics, it specifically deals with how pressure is transmitted through a fluid, not the buoyant force itself.
• Charles Augustine de Coulomb: A French physicist. He is best known for formulating Coulomb's Law, which describes the electrostatic interaction between electrically charged particles. This is unrelated to fluid mechanics or buoyancy.
• Isaac Newton: An English mathematician, physicist, astronomer, theologian, and author. He formulated the laws of motion and universal gravitation. While his work is foundational to physics, the specific principle explaining buoyant force is not attributed to him.

Based on these contributions, Archimedes is the physicist famous for explaining the existence and magnitude of the buoyant force through his principle.

Archimedes' Principle and Buoyant Force

Archimedes' Principle states that any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object. The buoyant force ($\text{F}_b$) can be calculated using the formula:

\( \text{F}_b = \rho_f \cdot V_{disp} \cdot g \)

Where:

• \( \rho_f \) is the density of the fluid
• \( V_{disp} \) is the volume of the fluid displaced by the object (which is equal to the volume of the submerged part of the object)
• \( g \) is the acceleration due to gravity

This principle directly explains why objects float or sink. An object floats if the buoyant force is equal to its weight, and it sinks if the buoyant force is less than its weight. If the buoyant force is greater than its weight, the object accelerates upwards until part of it emerges from the fluid, reducing the displaced volume until the buoyant force balances the weight.

Therefore, it is clear that Archimedes is the physicist credited with explaining buoyant force.

Revision Table: Key Physicists and Concepts

Additional Information: Buoyancy Explained Further

Buoyancy arises because the pressure in a fluid increases with depth. When an object is submerged, the pressure on its bottom surface is greater than the pressure on its top surface. This pressure difference results in a net upward force, which is the buoyant force. The volume of fluid displaced is crucial because it determines the weight of that displaced fluid, which, according to Archimedes' Principle, is equal to the buoyant force.

Consider an object submerged in water. The water pressure pushes on all surfaces of the object. However, since the pressure is higher at greater depths, the upward forces on the lower part of the object are stronger than the downward forces on the upper part. The overall effect is an upward buoyant force.

Density plays a key role. An object floats if its average density is less than the density of the fluid. It sinks if its average density is greater than the fluid's density. If the densities are equal, the object remains suspended at any depth within the fluid.