Standard Science Primary 4 Energy

Gaps are often left between the sections of railway tracks. What is the main purpose of these gaps?

A To allow the tracks to contract on a cold day without snapping.
B To allow the tracks to expand on a hot day without buckling.
C To make the train move faster.
D To reduce the amount of iron needed to build the tracks.
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Worked Solution

Step 1: Identify that metal tracks gain heat from the sun. Step 2: Heat gain causes solids to expand (increase in volume/length). Step 3: Without gaps, expanding tracks would press against each other and bend (buckle).

Correct answer: To allow the tracks to expand on a hot day without buckling.

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