3.9 growing in the heat

3.9 Growing in the heat13 April 2023

What happened here?

Aims

• Describe the expansion of materials• Explain the expansion and contraction

The future?

• Global warming is causing the average temperature of the Earth’s oceans to increase

• As the seawater gets hotter it expands, this makes the sea levels increase over time

• Many low level islands will be covered in water in the future

Solids

• Like sea-water, solids also expand when heated• The particles do not change size

– When a solid is heated the particles move faster and they take up more space. The solid expands.

– When a solid is cooled, the particles slow down and take up less space. The solid contracts.

Liquids

• When a liquid heats up the particles move around faster, they take up more space and the liquid expands

• When a liquid cools down the particles move slower and take up less space, the liquid contracts

Gases

• Gases take up more space when heated, hot air balloon are filled with hot air, this is less dense than the outside cold air, it rises.

• You can make the balloon go higher by heating the gas more.

3.9 Growing in the heatQuestions

1. a. Why can a steel rod fit into a small hole if the rod is first cooled down?

b. Why will the rod get stuck in the hole when the rod warms up again?

2. You can store food in a plastic container in the fridge. What happens to the air in the container as it cools down?

3. Suggest why an oven door is not exactly the same size as the opening to the oven.

(Level 3)

(Level 3)

(Level 4)

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3.9 Growing in the heatQuestions

4. Concorde was a supersonic airliner built by Britain and France. It flew so fast that it warmed up during flights. Suggest why a gap opened up between a control panel and the wall on Concorde’s flight deck during flight.

5. Using the idea of particles, explain why hot air balloons get smaller as the air inside them cools down.

6. Using the idea of particles, suggest why pipes can burst in winter when the water inside them freezes.

(Level 5)

(Level 6)

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(Level 7)

3.9 Growing in the heatQuestions

7. The metal lids on glass jars can sometimes get stuck. They can often be unscrewed after running hot water over them. a. Which is likely to expand most in the heat,

the lid or the jar? b. Use the idea of particles to explain your

answer.

(Level 7)

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3.9 Growing in the heatFor your notes

Solids, liquids and gases expand when they are heated.

Their particles stay the same size but take up more space when they are heated.

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