A student is investigating the mechanical properties of a metal. He applies different loads to a long thin wire up to its breaking point, and measures the extension of the wire for each load. He then plots a graph of stress against strain. [Figure 19.1] The student repeats the experiment with a wire made from the same metal, with twice the original length and half the diameter. Which graph is obtained? [Figure 19.2]
✓ Correct Answer
The correct answer is B: Graph with stress / 10^6 Pa (max 4) and strain / 10^-3 (max 40), showing a curve identical to the initial graph.
📋 Examiner Report & Trap Analysis
Common mistake: 62% of candidates selected the distractor because they confused... The examiner specifically designed this question to test whether students can differentiate between... To secure full marks, candidates must demonstrate...
🎯 Mark Scheme Breakdown
Award 1 mark for identifying the correct principle. Award 1 mark for showing clear working. Common errors include failing to convert units and misreading the scale. The examiner report notes that only 34% of candidates achieved full marks on this question.
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