A-LevelPhysicsDynamicsOct/Nov 2011Paper 1 Q101 Mark
A group of students investigating the principle of conservation of momentum use a small truck travelling over a frictionless surface. Sand is dropped into the truck as it passes X. At Y, a trapdoor in the bottom of the truck opens and the sand falls out. [Figure 10.1] How does the velocity of the truck change when the sand is added to the truck at X and then leaves the truck at Y?
Adecreases at X, increases at Y
Bdecreases at X, stays the same at Y
Cstays the same at X, increases at Y
Dstays the same at X, stays the same at Y
✓ Correct Answer
The correct answer is B: decreases at X, stays the same at Y
📋 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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