Advanced Science Primary 4 Energy

Ravi found it difficult to open a glass jar with a tight metal lid. His father suggested pouring hot water over the metal lid. Why did this help?

A The metal lid expanded more than the glass jar.
B The glass jar expanded more than the metal lid.
C The metal lid contracted when it gained heat.
D The hot water acted as a lubricant.
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Worked Solution

Step 1: Metals are better conductors and expand more easily than glass when heated. Step [2-9]: Heating the lid causes it to expand, making the fit looser.

Correct answer: The metal lid expanded more than the glass jar.

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