Physics 2008 JAMB Past Questions - Question 17: When cold water is poured on a can containing hot water ,the can collapses because the

Correct Answer

D

Explanation

When cold water is poured onto a can containing hot water, the can can collapse due to a phenomenon known as thermal shock. Here's what happens:

1. **Thermal Expansion**: When you have hot water inside the can, both the water and the can itself are hot. Heat causes materials to expand. In this case, the can expands as it absorbs the heat from the hot water inside.

2. **Cold Water Addition**: When you pour cold water onto the can, it rapidly cools the exterior surface of the can. As the temperature of the can's surface decreases, it begins to contract, or shrink.

3. **Differential Contraction**: Now, you have a situation where the inside of the can is still hot and expanding, while the outside is rapidly cooling and contracting. This differential contraction can lead to the can collapsing, especially if it happens suddenly and the can isn't designed to withstand this type of thermal stress.

4. **Air Pressure**: Additionally, the drop in temperature can cause the air inside the can to contract. As the air pressure inside the can decreases, it can contribute to the collapse of the can.

This phenomenon can be demonstrated with various materials and objects, not just cans. It illustrates the importance of gradual temperature changes and why sudden and extreme temperature differences can lead to structural failure in materials.