The diagram shows a child X of mass 20 kg and a child Y of mass 15 kg seated on a uniform plank. [Figure 9.1] The plank has a mass of 7.0 kg and has a pivot at its midpoint. The plank is horizontal and in equilibrium. Which statement about the weight of the plank is correct?
✓ Correct Answer
The correct answer is A: The weight of the plank can be considered to be acting at its midpoint.
📋 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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