Question

Two objects of exactly the same size and shape, one made of wood and the other made of steel, are placed in a container of water. The wood object floats and the steel object sinks to the bottom of the container. Which one of the following statements is TRUE?

1) Both objects experience the same magnitude of buoyant force.
2) The buoyant force on the wood object is directed upward and the buoyant force on the steel object is directed downward.
3) The buoyant force on both objects is directed downward.
4) The magnitude of the buoyant force on the wood object is greater than on the steel object.
5) The magnitude of the buoyant force on the steel object is greater than on the wood object.

Answer 1

The correct statement regarding the two objects of the same size and shape, one made of wood and the other made of steel, placed in a container of water is: Both objects experience the same magnitude of buoyant force. This correct option is statement 1.

Step-by-step explanation:

The correct answer is that both objects experience the same magnitude of buoyant force, which is upwards for any object in a fluid; however, the wood floats because it has a lesser density than water and the steel sinks due to its greater density.

When two objects of the same volume are placed in a fluid, they displace the same amount of fluid and hence, according to Archimedes' principle, they experience the same magnitude of buoyant force. However, whether an object sinks or floats depends on its density compared to the density of the fluid. The wood floats because its density is less than that of water, and hence, the buoyant force is sufficient to support its weight.

In contrast, the steel sinks because its density is greater than water, and the buoyant force is not sufficient to overcome the weight of the steel. The direction of the buoyant force is always upwards for any object submerged in a fluid.

Thus, the correct answer is option 1.