Two cylinders, one made of lead (density $11,340 \mathrm{~kg} / \mathrm{m}^{3}$ ) and one of copper (density $8,940 \mathrm{~kg} / \mathrm{m}^{3}$ ), have the same radius and height. They are thrown into a pool of water (density $1,000 \mathrm{~kg} / \mathrm{m}^{3}$ ) and sink to the bottom. As they are sinking, describe the buoyant forces on the cylinders.
A) The buoyant force on the copper cylinder is greater than that on the lead.
B) There is no buoyant force on either, as they are sinking.
C) The buoyant force is the same on each cylinder.
D) The buoyant force on the lead cylinder is greater than that on the copper.

Question

Quizplus · Accepted Answer

The buoyant force depends on the volume of fluid displaced by an object, not its mass or material. Since both cylinders have the same volume (same radius and height), they displace the same amount of water and experience the same buoyant force.

Two Cylinders, One Made of Lead (Density 11,340 kg/m311,340 \mathrm{~kg} / \mathrm{m}^{3}11,340 kg/m3

Two Cylinders, One Made of Lead (Density $11,340 \mathrm{~kg} / \mathrm{m}^{3}$