Pressure and Depth
2 marks · NormalExplain why the pressure at the bottom of a swimming pool is greater than at the surface. Refer to molecules and the pressure-depth relationship.
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Must show: deeper means greater weight of water above, pressure increases with depth due to more molecules above exerting force
Also accept: increased weight with depth; molecules above create push
Common mistakes: confusing with density changes
Show mark scheme and worked solution
Marking points
B1 · 1 mark · States that pressure increases with depth/greater weight of liquid above.
B2 · 1 mark · Mentions more liquid molecules exert force down at greater depth, or pressure is caused by weight of molecules above.
Worked solution
At greater depth, there is more liquid above, so the weight pressing down is greater and pressure is higher. More molecules are above each point at greater depth, causing a greater force on the area.