Pressure and depth

4 marks · Normal

A diver is swimming in a freshwater lake. The density of freshwater is . The gravitational field strength is .

(a)

Calculate the pressure difference between the surface and a point 3.5 m below the surface.

[3 marks]

(b)

State two factors that would cause the pressure at the same depth in another liquid to be greater.

[1 mark]

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(a) 35000 Pa · must show correct substitution, evaluation

(b) Greater density, greater gravitational field strength · must show density, gravity

Common mistakes: Using wrong density or g

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Marking points

M1 (a) · 1 mark · Substitute h=3.5, ρ=1000, g=10 into p = hρg

A1 (a) · 2 marks · Calculate correct pressure difference (35000 Pa) (follow-through)

B1 (b) · 1 mark · State correct factors (any two: higher density or higher g)

Worked solution

a) Use . Pa

b) Greater density (), greater gravitational field strength (g).