A-LevelPhysicsDynamicsFeb/Mar 2019Paper 1 Q81 Mark
Two balls X and Y are moving towards each other with speeds of 5 m s⁻¹ and 15 m s⁻¹ respectively. [Figure 8.1] They make a perfectly elastic head-on collision and ball Y moves to the right with a speed of 7 m s⁻¹. What is the speed and direction of ball X after the collision?
A3 m s⁻¹ to the left
B13 m s⁻¹ to the left
C3 m s⁻¹ to the right
D13 m s⁻¹ to the right
✓ Correct Answer
The correct answer is B: 13 m s⁻¹ to the left
📋 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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