A sealed glass vial is placed in a beaker of water and sinks. Without opening the vial, a researcher attaches a lightweight foam collar around the vial, increasing the total volume of the vial+collar system with negligible change in total mass. The system is returned to water. Based on Archimedes' Principle, which outcome would be expected?
- The vial+collar system is more likely to float because the increased displaced water volume increases buoyant force while weight is nearly unchanged. (correct answer)
- The vial+collar system is more likely to sink because increasing volume increases gravitational force on the system.
- The vial+collar system behaves the same because buoyant force depends only on the vial's original glass density.
- The vial+collar system floats only if the foam increases surface tension at the waterline enough to support the weight.
Explanation: This question tests understanding of buoyancy and Archimedes' Principle in the MCAT Chemical & Physical Foundations of Biological Systems section. Archimedes' Principle states that the buoyant force on an object is equal to the weight of the fluid displaced by the object. Adding the lightweight foam collar significantly increases the system's total volume with negligible mass increase. Choice A is correct because the increased volume displaces more water, increasing buoyant force (F_b = ρ_water × V_displaced × g) while the weight remains nearly unchanged, making the system more likely to float when buoyant force exceeds weight. Choice B is incorrect because it falsely claims that increasing volume increases gravitational force, when gravity acts only on mass. To determine if modifications will make an object float, compare the change in buoyant force (from increased volume) to any change in weight.