Advanced Science Primary 4 Energy

Siti found it difficult to open a glass jar with a metal lid. She poured hot water over the metal lid for a minute and was then able to open it easily. Why?

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

Worked Solution

Step 1: Metal is a better conductor of heat than glass. Step 2: The metal lid gains heat and expands faster/more than the glass. Step 3: This loosens the grip of the lid on the jar.

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

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