Explain why a diver experiences greater pressure when swimming at the bottom of a deep swimming pool compared to just below the surface.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
A diver is training in a swimming pool. She notices that the pressure she feels on her body increases as she swims deeper.
Model answer (4 marks)
Pressure in a liquid rises with depth because the weight of the water above exerts a force on the fluid.
At a greater depth the diver is surrounded by a taller column of water, so the weight of that column is larger.
The weight of the water above the diver creates a downward force on her body, increasing the pressure she feels.
The pressure difference between the top and bottom of her body (the up‑thrust) is also larger at depth, adding to the overall pressure.
At a greater depth the diver is surrounded by a taller column of water, so the weight of that column is larger.
The weight of the water above the diver creates a downward force on her body, increasing the pressure she feels.
The pressure difference between the top and bottom of her body (the up‑thrust) is also larger at depth, adding to the overall pressure.
Examiner tips
- Use the phrase "pressure increases with depth" first. Mention the taller column of water and its weight. Explain the resulting downward force. Include the up‑thrust/pressure difference at depth.
Common mistakes
- Confusing pressure with force; not linking weight to pressure. Forgetting to mention the column of water. Using vague terms like "more pressure" without explanation.
Mark scheme (4 marks)
- Pressure in a liquid increases with depth
- There is a greater (taller) column of water above the diver at greater depth
- The weight of the water above acts on the diver, producing a downward force / contributing to the pressure
- Upthrust / pressure difference between top and bottom of the diver is also greater at depth
Key terms in this question
Related
- All AQA GCSE Physics (8463) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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