The topic here is pressure in a liquid. Water has a density of 1000 kg/m3, and the gravitational field strength is 10 N/kg.
14[1 mark]
The diver sinks from 3.0 m depth down to 7.0 m depth. Find the increase in water pressure, in Pa.
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4000 pascals
30 000 pascals
40 000 pascals
70 000 pascals
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The diver goes down:. 7.0 − 3.0 = 4.0 m. Pressure change = height × density × gravitational field strength. = 4.0 × 1000 × 10. = 40 000 Pa. That is the third option. 4000 Pa leaves out the field strength, 4.0 × 1000. 30 000 Pa is the pressure at 3.0 m only, and 70 000 Pa is the pressure at 7.0 m. Both of those are pressures at one depth, not the change between the two depths.
1 mark
How the marks are earned
- Choose 40 000 pascals: the change in depth is 4.0 m, and pressure change = height × density × gravitational field strength = 4.0 × 1000 × 10.
- The right option alone earns the mark with no working needed. One answer only: two answers earn nothing, and a circled or underlined right option counts if the box is blank.