You may use a calculator. You should show all your working and use appropriate units. Take the weight of 1.0 kg to be 9.8 N (acceleration of free fall = 9.8 m/s²).
(a)
One type of renewable energy source is shown in Fig. 4.1.
State the name of the renewable energy source shown in Fig. 4.1.
Answer guidance
State A short answer. No explanation is needed, and adding one cannot earn extra marks.
[1 mark]
(b)(i)
1000 kg of cold water at a temperature of 20 °C is pumped down to the hot rocks.
The water returns partly as steam and partly as hot water.
The steam and the hot water are both at a temperature of 100 °C.
The specific heat capacity of water is 4200 J / (kg °C).
Calculate the energy needed to heat 1000 kg of water from 20 °C to 100 °C.
energy = ...................................... J
Answer guidance
Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.
[2 marks]
(b)(ii)
Explain why more energy is transferred when 1 kg of the steam cools to 20 °C than when 1 kg of the hot water cools to 20 °C.
You should include a reference to the arrangement of particles in liquids and in gases in your answer.
Answer guidance
Explain Give reasons, not just what happens. Each distinct reason is usually worth a mark.
[3 marks]
5054/02/SP/23Cambridge O Level Physics 5054 · Specimen 2023 · Paper 2 · Question 4