A-LevelPhysicsDeformation of solidsOct/Nov 2015Paper 1 Q241 Mark
A 0.80 m length of steel wire and a 1.4 m length of brass wire are joined together. The combined wires are suspended from a fixed support and a force of 40 N is applied, as shown. [Figure showing a steel wire joined to a brass wire, suspended from a support, with a 40N force applied] The Young modulus of steel is 2.0 × 10¹¹ Pa. The Young modulus of brass is 1.0 × 10¹¹ Pa. Each wire has a cross-sectional area of 2.4 x 10⁻⁶ m². The wires extend without reaching their elastic limits. What is the total extension? Ignore the weights of the wires.
A1.7 × 10⁻⁴ m
B3.0 × 10⁻⁴ m
C3.9 × 10⁻⁴ m
D9.0 × 10⁻⁴ m
✓ Correct Answer
The correct answer is B: 3.0 × 10⁻⁴ m
📋 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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