Question

A combination of wood and iron is just floating in the water. State your observations and explain, what will happen if the water is gently heated.

Answer 1

Observations before heating the water

1. When the combination of wood and iron is just floating in the water, buoyant force will act on the combination in the opposite direction of the weight of the combination.
2. Since the combination just floats in water, the buoyant force on the combination will be equal to the weight of the combination.

Observations after heating the water gently

1. When the water is gently heated, the molecules of the water gain kinetic energy and start moving away from each other at a faster rate which causes an increase in the volume of the water.
2. Due to the increase in the volume of the water, the density of the water will decrease because density is inversely proportional to the volume.
3. The buoyant force acting on the combination will decrease due to a decrease in the density of the water because buoyant force is directly proportional to the density of the liquid.
4. Ultimately, the weight of the combination exceeds the buoyant force, and the combination of wood and iron sinks.