A-LevelPhysicsForces, density and pressureMay/June 2025Paper 1 Q141 Mark
A wooden block is held stationary in a container of water using a string that is attached to both the wooden block and the bottom of the container. [Diagram shows a container of water with a wooden block submerged and held down by a string attached to the bottom.] The wooden block has mass m and volume V. The water has density ρ. The acceleration of free fall is g. What is the magnitude of the force acting on the block due to the tension in the string?
AρgV
Bmg + ρgV
Cmg
DρgV - mg
✓ Correct Answer
The correct answer is D: ρgV - mg
📋 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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