Physics 5054 · O Level · Pressure

Pressure — practice question

A small aircraft lifts off from the level deck of a ship. Before it can take off, a holdback bar keeps the aircraft fixed in position. Once the holdback bar is let go, the aircraft is drawn along the deck by a steam-driven piston, as shown in Fig. 2.1. The steam applies a very large pressure to the piston.
(a(i))[2]

Explain, using ideas about particles, how the steam produces a pressure on the piston.

(a(ii))[2]

Explain why the pressure on the piston rises when the temperature of the steam increases.

(b)[2]

When the pressure becomes high enough, the holdback bar is released. The steam forces the piston along the pipe shown in Fig. 2.1. The piston has a cross-sectional area of $0.30\,\text{m}^2$. The pressure of the steam in the tank is $2.1 \times 10^6\,\text{Pa}$. Atmospheric pressure is $1.0 \times 10^5\,\text{Pa}$. Determine the resultant force on the piston caused by the pressure difference. Show your working.

(c(i))[2]

The force found in (b) makes the aircraft accelerate from rest up to a maximum speed of $28\,\text{m s}^{-1}$. The mass of the aircraft is $3.0 \times 10^4\,\text{kg}$. Calculate the momentum of the aircraft at the maximum speed.

(c(ii))[2]

Calculate the time needed for the aircraft to reach the maximum speed.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Particles strike the piston or the container walls

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