A glass jar lid that is stuck can often be loosened by running hot water over the metal lid. This works because:

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Question

A glass jar lid that is stuck can often be loosened by running hot water over the metal lid. This works because:

Accepted Answer

B. Metal expands more than glass, so the lid enlarges relative to the jar — Metals generally have a larger coefficient of thermal expansion than glass. When hot water is applied to the metal lid, the lid expands more than the glass jar, slightly increasing the diameter of the lid's grip ring and loosening it from the jar threads. This is a direct application of differential thermal expansion between materials.

Answer

A. Hot water softens the metal making it easier to grip

Answer

C. Hot water causes the glass to contract more than the metal lid

Answer

D. Metal becomes magnetic when heated making it easier to remove

Answer

B. Metal expands more than glass, so the lid enlarges relative to the jar

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