A-LevelPhysicsForces, density and pressureFeb/Mar 2022Paper 1 Q131 Mark
A rigid sphere is held at rest on the sea bed. When the sphere is released, it rises to the surface of the sea. The seawater has a uniform density. Which statement about the sphere, from its release until it reaches the surface, is correct?
AThe sphere always moves with constant acceleration.
BThe sphere always moves with constant velocity.
CThe upthrust on the sphere always decreases.
DThe upthrust on the sphere is always constant.
✓ Correct Answer
The correct answer is D: The upthrust on the sphere is always constant.
📋 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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