1. 1
   A woman weighing 600 N stands still, balanced on the narrow heel of one shoe, which has a contact area of 0.0005 m2. She then puts on a pair of wide snowshoes, each with a much larger contact area of 0.2 m2, before walking onto soft snow.

   (a)

   What pressure does she exert on the ground through this heel?

   [1 mark]

   • A300 Pa
   • B0.0000008 Pa
   • C600.0005 Pa
   • D1200000 Pa

   (b)

   The same woman then puts on a pair of wide snowshoes, each with a contact area of 0.2 m2, before walking onto soft snow. Compared with the narrow heel, what happens to the pressure she exerts on the ground?

   [1 mark]

   • AThe pressure stays exactly the same
   • BThe pressure is much higher, since the contact area is much greater
   • CThe pressure is much lower, since the contact area is much greater
   • DThe pressure becomes zero

   (c)

   Explain, using the equation for pressure, why wearing snowshoes stops the woman from sinking into soft snow, whereas standing on a narrow heel would cause her to sink in.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A diver descends 8 m below the surface of a swimming pool, where the water has a density of 1000 kg/m3 and the gravitational field strength is 9.8 N/kg.

   (a)

   What additional pressure, due to the water above, does the diver experience at this depth compared with the surface?

   [1 mark]

   • A78400 Pa
   • B9800 Pa
   • C8000 Pa
   • D1.225 Pa

   (b)

   As the diver continues to descend further below the surface, what happens to the pressure they experience due to the water above them?

   [1 mark]

   • AIt continues to decrease
   • BIt continues to increase
   • CIt stays exactly the same at all depths
   • DIt becomes zero once the diver is fully submerged

   (c)

   Describe, qualitatively, how the pressure beneath the surface of a liquid depends on both the depth below the surface and the density of the liquid.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   An engineer is designing a large water dam, and is also comparing the pressure at the same depth in two different liquids used elsewhere in the plant: water (density 1000 kg/m3) and a denser brine solution (density 1200 kg/m3).

   (a)

   An engineer is designing a large water dam. Explain, in terms of pressure, why the dam wall is built much thicker at the bottom than at the top.

   [3 marks]

   (b)

   The engineer compares the pressure due to the liquid at a depth of 5 m in water (density 1000 kg/m3) with the pressure at the same depth of 5 m in a denser brine solution (density 1200 kg/m3), using a gravitational field strength of 9.8 N/kg. Calculate the pressure due to the liquid at this depth in each liquid, and explain why the two values are different.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A cooking equipment designer is comparing how easily sharp and blunt knife blades cut food. Separately, an ocean engineering team is designing the hull of a deep-sea submersible that will operate at depths of both 200 m and 2000 m in seawater of density 1030 kg/m3.

   (a)

   Explain, using the equation p = F/A, why a sharp knife blade cuts through food much more easily than a blunt knife pressed with the same force, and calculate the pressure exerted by a sharp blade with a contact area of 0.0000004 m2 when a force of 12 N is applied, comparing this with the pressure exerted by a blunt blade of contact area 0.00002 m2 under the same force.

   [6 marks]

   (b)

   An ocean engineering team is designing the hull of a deep-sea submersible that must withstand water pressure at both 200 m and 2000 m depth in seawater of density 1030 kg/m3 (gravitational field strength 9.8 N/kg). Calculate the pressure due to the water at each of these two depths, and explain why the submersible's hull must be built far stronger to survive at 2000 m than it would need to be to survive only at 200 m.

   [6 marks]

   Total for question 4: 12 marks

End of questions