Houses in cold countries have thicker walls. Why?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Environment:** In cold countries, the external environment has a lower temperature (T1) compared to the temperature inside the house (T2). This temperature difference creates a situation where heat tends to flow from the warmer area (inside the house) to the colder area (outside).

2. **Heat Transfer Direction:** The heat transfer will occur from the inside of the house to the outside environment due to the temperature gradient. This means that the warmth from the room is trying to escape into the colder outside air.

3. **Role of Wall Thickness:** To minimize the loss of heat from the room to the outside, houses in cold countries are built with thicker walls. A thicker wall provides more material for heat to pass through, which slows down the rate of heat transfer.

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