A-LevelPhysicsForces, density and pressureOct/Nov 2019Paper 2 Q311 Marks
A small remote-controlled model aircraft has two propellers, each of diameter 16cm. Fig. 3.1 is a side view of the aircraft when hovering. [Figure 3.1] Air is propelled vertically downwards by each propeller so that the aircraft hovers at a fixed position. The density of the air is 1.2kgm⁻³. Assume that the air from each propeller moves with a constant speed of 7.6ms⁻¹ in a uniform cylinder of diameter 16cm. Also assume that the air above each propeller is stationary.
📋 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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