---
title: "An experimenter has two solid spheres, Sphere 1 and Sphere 2, which have the same volume but are made of different materials. Sphere 1 is made of aluminum (density \\(\\rho_{Al} = 2700 \\text{ kg/m}^3\\)) and Sphere 2 is made of lead (density \\(\\rho_{Pb} = 11300 \\text{ kg/m}^3\\)). Both spheres are held fully submerged at the same depth in a large tank of water. Which of the following correctly compares the magnitude of the buoyant force \\(F_B\\) exerted by the water on the spheres and provides a correct justification?"
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url: "https://nerd-notes.com/ubq/110797/"
date_modified: "2026-04-08T03:12:09+00:00"
---

# An experimenter has two solid spheres, Sphere 1 and Sphere 2, which have the same volume but are made of different materials. Sphere 1 is made of aluminum (density \(\rho_{Al} = 2700 \text{ kg/m}^3\)) and Sphere 2 is made of lead (density \(\rho_{Pb} = 11300 \text{ kg/m}^3\)). Both spheres are held fully submerged at the same depth in a large tank of water. Which of the following correctly compares the magnitude of the buoyant force \(F_B\) exerted by the water on the spheres and provides a correct justification?

An experimenter has two solid spheres, Sphere 1 and Sphere 2, which have the same volume but are made of different materials. Sphere 1 is made of aluminum (density \(\rho_{Al} = 2700 \text{ kg/m}^3\)) and Sphere 2 is made of lead (density \(\rho_{Pb} = 11300 \text{ kg/m}^3\)). Both spheres are held fully submerged at the same depth in a large tank of water. Which of the following correctly compares the magnitude of the buoyant force \(F_B\) exerted by the water on the spheres and provides a correct justification?

![A rectangular tank filled with water. Inside the tank, two identical-sized spheres are shown side-by-side at the same horizontal level, completely underwater. Sphere 1 is labeled 'Aluminum' and Sphere 2 is labeled 'Lead'. Both are suspended by thin strings from above.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1775617929-u0aGod.jpg)

- **A.** The buoyant force on Sphere 1 is greater than the buoyant force on Sphere 2 because the aluminum is less dense and thus more buoyant than lead.
- **B.** The buoyant force on Sphere 2 is greater than the buoyant force on Sphere 1 because lead is much denser and more force is required to support its greater weight.
- **C.** The buoyant forces on both spheres are equal because both spheres displace the same volume of water.
- **D.** The buoyant forces on both spheres are equal because they are submerged at the same depth and pressure is only a function of depth.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/110797/*