Foundation Science Primary 4 Energy

A metal rod is placed over a Bunsen burner flame. What happens to the length of the metal rod?

A The metal rod becomes longer because it gains heat and expands.
B The metal rod becomes shorter because it gains heat and contracts.
C The metal rod stays the same length because metal does not change with heat.
D The metal rod becomes shorter because it loses heat and contracts.
Show Worked Solution

Worked Solution

Step 1: Identify what is happening to the metal rod. The rod is placed over a flame, so it GAINS heat. Step 2: Recall the effect of heat gain on materials. When a material gains heat, its particles gain energy, move faster, and spread further apart — the material EXPANDS. Step 3: Apply to the metal rod. The metal rod gains heat → it expands → it becomes longer. Answer: The metal rod becomes longer because it gains heat and expands.

Correct answer: The metal rod becomes longer because it gains heat and expands.

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