Why might a dish crack when placed in hot water?

When a dish is placed in hot water, it can experience thermal shock, which is the rapid change in temperature of the material. This sudden temperature difference can cause the dish to crack due to the following factors:

1. Coefficient of thermal expansion: Different materials expand at different rates when heated. The dish is usually made of ceramic, which has a relatively high coefficient of thermal expansion. When the dish is placed in hot water, the inner surface expands faster than the outer surface, creating internal stress within the material.

2. Thermal conductivity: Ceramic is generally a poor thermal conductor, meaning it does not transfer heat well. When the dish is placed in hot water, the outer surface heats up quickly while the inner surface remains relatively cool. This uneven heating creates a temperature gradient within the dish, leading to uneven expansion and stress.

3. Brittleness: Ceramic is a brittle material, which means it has low resistance to fracture under tensile stress. When the stress caused by thermal expansion exceeds the material's strength, it can cause cracks to form.

To prevent thermal shock and cracking, the following precautions can be taken:

- Avoid placing a cold dish directly into boiling or very hot water. Instead, gradually increase the water temperature by starting with warm water and gradually adding hotter water.

- Never place a dish directly over a heat source, such as a stovetop or campfire, as this can lead to rapid and excessive temperature changes.

- Use dishes specifically designed to withstand high temperatures, such as tempered glass or heat-resistant ceramic. These materials are more resistant to thermal shock and less prone to cracking.

By taking these precautions, you can reduce the risk of cracking your dishes when exposing them to hot water.