O-LevelPhysicsForces5054/22 · Oct/Nov 2015 · Q36 Marks

A very deep tank is used when training sailors to escape from submarines. The tank is cylindrical and open to the air at the top. Fig. 3.1 shows the tank. [Figure 3.1] (not to scale) The area of the base of the tank is 45 m² and the tank is filled with water to a depth of 32 m.

(a)The density of water is 1000kg/m³ and the gravitational field strength g is 10N/kg. Calculate the pressure, due to the water, on the base of the tank. pressure =[2]
(b)(i)The pressure in the water at the base of the tank is 4.2 × 10⁵ Pa. Explain why the pressure in the water at the base of the tank differs from the value calculated in (a).[1]
(b)(ii)Calculate the force exerted on the base of the tank. force =[2]
(c)Force is a vector quantity and pressure is a scalar quantity. State how a vector quantity differs from a scalar quantity.[1]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2015). The mark or mark type is shown in brackets.

[1] (p = )hpg or 32 × 1000 × 10
[1] 3.2 x 10⁵ Pa
[1] atmospheric pressure (is also acting on the surface of the water)
[1] (F = )pA or 4.2 × 10⁵ × 45 or 3.2 × 10⁵ × 45 or 1.44 × 10⁷
[1] 1.9/1.89 x 10⁷ N
[1] (vector) has a direction or scalar does not have a direction or (vectors) may cancel or scalars cannot cancel

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.