A-LevelPhysicsDeformation of solidsMay/June 2016Paper 1 Q211 Mark
A metal wire is attached at one end to a fixed point and a load is hung from the other end so that the wire hangs vertically. The load is increased from zero to 20 N. This causes the wire to extend elastically by 5.0 mm. The load is then reduced to 12N and the extension decreases to 3.0 mm. [Figure 21.1] How much strain energy is released during the unloading process?
A0.8 × 10⁻² J
B1.8 × 10⁻² J
C2.4 × 10⁻² J
D3.2 × 10⁻² J
✓ Correct Answer
The correct answer is D: 3.2 × 10⁻² J
📋 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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