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Water Pressure with Increasing Depth
The Mariana Trench is the deepest part of the Pacific Ocean. Figure 8 shows a submarine going to the bottom of the Mariana Trench.
The depth of the submarine increases.
Explain what happens to the pressure on the submarine.
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Marking points
- 1 States that the height, volume or mass of water above the submarine increases.
- 2 Links the greater water force / weight to an increase in pressure, or uses p = ρgh with constant density and gravitational field strength.
Full-mark answer
As the submarine goes deeper, the column of water above it becomes taller, so the weight of water and the force it exerts increase. Therefore the pressure on the submarine increases.
Why this answer loses marks
Pressure increases because the submarine is moving down.
Direction of motion is not the cause; greater depth means a taller, heavier water column above the submarine.