Theory: answer all nine questions. Show working and appropriate units; diagrams and alternative valid methods are marked against the original scheme.
(a)(i)The Fig. 2.1 pool is 2.1 m by 4.0 m, with water depth 0.80 m and density 1000 kg/m³. Show that the water mass is approximately 6700 kg.
Answer guidance
Show The result is given, so every step of the reasoning is what earns the marks.
[2 marks]
(a)(ii)Define pressure.
[1 mark]
(a)(iii)Using the Fig. 2.1 pool depth 0.80 m and water density 1000 kg/m³, calculate pressure on the base due to the water, in Pa. Take g = 9.8 N/kg.
Answer guidance
Using You must use the thing it names. An answer that reaches the right value another way may not score.
[2 marks]
(a)(iv)The Fig. 2.1 pool initially has water at 10 °C. It receives 5.1 × 10⁸ J; water specific heat capacity is 4200 J/(kg °C). Using the water mass from 2(a)(i), calculate its final temperature.
Answer guidance
Using You must use the thing it names. An answer that reaches the right value another way may not score.
[3 marks]
(b)(i)Explain, in terms of particle motion, why evaporation cools the Fig. 2.1 pool water.
Answer guidance
Explain Give reasons, not just what happens. Each distinct reason is usually worth a mark.
[2 marks]
(b)(ii)State two environmental changes that increase evaporation from the Fig. 2.1 pool.
Answer guidance
State A short answer. No explanation is needed, and adding one cannot earn extra marks.