Standard Science Primary 4 Energy

Why are there small gaps between the metal tracks of a railway line?

A To make the train move faster.
B To allow the tracks to expand on a hot day.
C To save on the cost of metal.
D To allow water to drain away.
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Worked Solution

Step 1: Metal tracks gain heat from the sun on hot days. Step 2: Solids expand when they gain heat. Step 3: Gaps provide space for expansion so the tracks do not buckle or bend.

Correct answer: To allow the tracks to expand on a hot day.

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