A-LevelPhysicsDynamicsMay/June 2020Paper 1 Q91 Mark
A mass m₁ travelling with speed u₁ collides with a mass m₂ travelling with speed u₂ in the same direction. After the collision, mass m₁ has speed v₁ and mass m₂ has speed v₂ in the same direction. The collision is perfectly elastic. [Figure 9.1] Which equation is not correct?
Am₁u₁² – m₁v₁² = m₂v₂² – m₂u₂²
Bv₂ + u₂ = v₁ + u₁
Cm₁(u₁ - v₁) = m₂(v₂ - u₂)
Dm₁(u₁ – v₁)² = m₂(u₂ - v₂)²
✓ Correct Answer
The correct answer is D: m₁(u₁ – v₁)² = m₂(u₂ - v₂)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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