A-LevelPhysicsDeformation of solidsFeb/Mar 2016Paper 1 Q191 Mark
The Young modulus of steel is twice that of copper. A 50 cm length of copper wire of diameter 2.0 mm is joined to a 50 cm length of steel wire of diameter 1.0 mm, making a combination wire of length 1.0 m, as shown. [Figure 19.1] The combination wire is stretched by a weight added to its end. Both the copper and the steel wires obey Hooke's law. What is the ratio \frac{\text{extension of steel wire}}{\text{extension of copper wire}}?
A4
B2
C1
D0.5
✓ Correct Answer
The correct answer is B: 2
📋 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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