Standard Science Primary 4 Energy

Why are there small gaps left between the sections of metal railway tracks?

A To allow the tracks to contract on a hot day.
B To allow the tracks to expand on a hot day.
C To save on the cost of metal materials.
D To let water drain through during rain.
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Worked Solution

Step 1: Metals gain heat from the sun on hot days. Step [2-9]: Gaining heat causes the metal to expand (increase in volume). Step [2-9]: Gaps provide space for this expansion to prevent the tracks from buckling.

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

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