Archimedes' principle states that the buoyant force on a submerged object equals the weight of the displaced fluid. Which statement best describes this principle?

• A. The buoyant force equals the weight of the displaced fluid.
• B. The buoyant force equals the weight of the object.
• C. Buoyant force results from fluid viscosity.
• D. Buoyancy is independent of the displaced fluid's weight.

Answer: (A)

The key idea is that the upward buoyant force comes from pressure differences in the fluid. In a submerged object, pressure is higher at the bottom than at the top, so the bottom pushes up harder than the top pushes down. When you add all those pressure forces around the object's surface, you get a net upward force that is exactly equal to the weight of the fluid that would fill the space the object occupies—the weight of the displaced fluid. This is Archimedes’ principle: the buoyant force equals the weight of the displaced fluid. The size of this force grows with the object's volume and the fluid's density; a larger volume or denser fluid means a larger buoyant force. It’s not determined by the object's weight, and it doesn’t come from viscosity—the buoyant effect is about the weight of the displaced fluid.