Physics 0625 · IGCSE · Kinetic particle model of matter

Kinetic particle model of matter — practice question

Fig. 3.1 shows a balloon filled with air. The air pressure at the balloon’s inner surface keeps the rubber stretched. Fig. 3.1: a balloon filled with air.
(a)[3]

Explain, in terms of the momentum of the molecules, why pressure acts at the inner surface of the balloon.

(b(i))[2]

Calculate the air volume when the pressure of the air is $1.4 \times 10^5\,\text{Pa}$.

(b(ii))[2]

Explain why the air volume in the balloon decreases when the temperature falls.

Worked solution & mark scheme

This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Molecules strike inner surface” …

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