AAMC FL Practice Exam

What defines the buoyant force on an object according to Archimedes' Principle?

1. The weight of the object in air

2. The weight of the fluid displaced by the object

3. The weight of the object in water

4. The volume of the object

The correct answer is: The weight of the fluid displaced by the object

The buoyant force on an object as defined by Archimedes' Principle is equal to the weight of the fluid displaced by that object. This principle states that when an object is immersed in a fluid, it experiences an upward force that is equal to the weight of the fluid it displaces. When an object is placed in a fluid, it pushes aside a volume of fluid equivalent to its submerged volume. The weight of that displaced fluid creates an upward force on the object, counteracting its weight. This is why an object may feel lighter when submerged; the buoyant force, determined by the weight of the fluid displaced, supports part of the object's weight. Understanding this principle is crucial in various applications, such as designing ships and submarines, determining if objects will float or sink, and even in understanding phenomena related to gases and aerodynamics. The other options do not directly relate to the concept of buoyancy defined by Archimedes' Principle. The weight of the object in air, the weight of the object in water, and the volume of the object itself do not account for the interaction with the fluid that generates the buoyant force.