Trapped air keeps us warm
Air is a poor conductor of heat.
Winter clothes
In winter we like to wear woollen clothes. We also like two thin blankets more than one thick blanket.
Why do you think wool and two thin blankets keep us warm?
What this lesson covers
The idea
Air is a poor conductor of heat, so air trapped in pores or between layers reduces the flow of heat from one side to the other.
Winter clothes
In winter we like to wear woollen clothes. We also like two thin blankets more than one thick blanket.
Why do you think wool and two thin blankets keep us warm?
- They trap air, and air does not let heat pass easily
- They make heat inside themselves
- They are always heavier
Pick a cover
Pick each cover and look at the arrows. They show heat flowing from the warm body to the cold outside.
Air in the way
Wool has tiny pores full of air. Two thin blankets have a layer of air between them. Air is a poor conductor of heat, so less heat flows out of our body.
Air is a poor conductor of heat, so air trapped in pores or between layers reduces the flow of heat from one side to the other.
Notes
Air is a poor conductor of heat, so air trapped in pores or between layers reduces the flow of heat from one side to the other.
Check yourself
Why does woollen cloth keep us warm in winter?
Why do we prefer two thin blankets to one thick blanket?
Houses in the Himalayas have walls with two wooden layers filled with cow dung and mud. This helps because wood and mud are …
Air trapped in hollow bricks keeps a house warm in winter and cool in summer because air is …
- It traps air in its pores, and air is a poor conductor of heat — correct. Yes!
- Wool is a good conductor, so it gives us heat. Wool does not make heat. The trapped air slows the heat going out of our body.
- Wool has no pores. Wool has many pores, and the air in them is what helps.
- The thick blanket has more air in it. One thick blanket has no layer of air in the middle. The layer of air between two thin blankets cuts the flow of heat.
- The air between the two thin blankets is a poor conductor of heat — correct. Yes!
- Two blankets make more heat. Blankets do not make heat. The air between them reduces heat loss.
- good conductors of heat. Good conductors would let the heat go out. Wood and mud are poor conductors, so the house stays warm.
- sources of heat. They do not give out heat. They stop heat from escaping.
- poor conductors of heat — correct. Yes!
- a poor conductor of heat — correct. Yes!
- a good conductor of heat. If it were, the hollow bricks would not help.
- a very hot gas. Air in the bricks is not hot. Its job is to slow down the flow of heat.