Advanced Science Primary 4 Energy

When a metal lid on a glass jar is too tight to open, Sara pours hot water over the metal lid. Why does this help?

A The metal lid contracts and becomes loose.
B The metal lid expands more than the glass jar.
C The glass jar expands more than the lid.
D The hot water acts as a lubricant.
Show Worked Solution

Worked Solution

Step 1: Metal is a better conductor of heat than glass. Step 2: The lid gains heat and expands (increases in size). Step 3: Since the lid expands more/faster than the jar, it becomes loose.

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

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