A cube with side $0.040\,\text{m}$ is floating in a container of liquid. In Fig. 3.1, the liquid surface is $0.028\,\text{m}$ above the level of the cube’s bottom face. The diagram is labelled air, cube, liquid, valve, pump, and the dimensions $0.040\,\text{m}$ and $0.028\,\text{m}$. Air above the cube exerts a force on the cube’s top face. The valve remains closed.
(a)[3]
Explain, in terms of air molecules, how the force caused by the pressure of the air is produced.
(b(i))[2]
Calculate the pressure caused by the liquid at a depth of $0.028\,\text{m}$.
(b(ii))[2]
Calculate the force on the bottom face of the cube due to the pressure of the liquid.
(c(i))[2]
Calculate the work done on the cube by the force in (b)(ii).
(c(ii))[1]
Suggest one reason why this is not an efficient way to lift the cube.
Worked solution & mark scheme
This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Air molecules move about / collide” …